Basic principles of image sensors - CCD chip size

Although each manufacturer provides a sensor and pixel size slightly different, the nominal sizes of 640 x 480 matrix are given in table 2. BasicprinciplesofimagesensorsIntroductionHistoricalsummaryBasicglossaryImagesensorsIntroductionCCDmatricesCCDworkingMatrixarchitectureLinearmatricesFullframetransfermatricesFrametransferInterlinetransferProgressivescanTimedelayandintegrationCCDsensornoiseDarkcurrentBloomingQuantumefficiencyTransportandconversionofthechargeCCDchipsizeDefectsSizeandarchitectureCMOSsensorsNoisequantificationComparisonofCCDsandCMOSsUsesandprecautionsCasestudyReferencesCCDchipsize Historically,vacuumtubes“vidicon”usedforprofessionaltelevisionapplicationswerecharacterizedbythediameterofthetube.Inordertominimizethedistortionandthenonuniformitiesofthetube,therecommendedsizeoftheimagewasconsiderablysmallerthethediameterofthecompletetube.WhenCCDsreplacedthetubes,theCCDindustrymaintainedtheimagesizebutalsocontinuedtousethenomenclatureoftubes.(Table1). Table1:CCDmatricesizeforstandardformats [zoom...]Info Althougheachmanufacturerprovidesasensorandpixelsizeslightlydifferent,thenominalsizesof640x480matrixaregivenintable2.Thesepixelstendtobesquare.However,andinparticularforinterlinetransfersystems,approximatelyhalfofthepixelisdedicatedtotheverticalshieldedtransferregister.Itmeansthattheactivewidthofthedetectorishalfthewidthofthepixel.Thus,theactivesurfaceofapixelisrectangularwithinterlinetransfersystems.Forprofessionalsofvideo,thisasymmetrydoesnotcomeasasourceofsignificantdisruptionoftheimagequality.However,itisgoodtoknowthisfactinscientificapplicationsincludingtheuseofimagecorrelationorstereophotogrammetry. Thedecreaseinopticalformatislinkedtocost.ThepriceofCCDsisprincipallydeterminedbythemanufacturingcostofwafersofsemiconductors.Whenthesizeofthechipdecreases,itispossibletoplacemorematricesonasamewaferandthismakesthericeofeachindividualchipdecrease.Thetendencytoreducethesizeofthechipswillprobablycontinueaslongasopticalandelectricalperformancesofimagingsystemsdonotchange.However,smallerpixelsreducethesizeofthechargewell.Foragivenluminousfluxandaperture,thesmallestsensorswillhavealowersensitivity. Table2:Nominalsizeofthepixel,format640x480 [zoom...]Info Smallerchipsgeneratesmallercameras.However,inordertomaintaintheresolution,onlythepixelscanbesmall.Here,thecompromiseisrelativetothesizeofthepixel,tothefocaldistanceandtothetotalsizeofthechip. Thetable3showsthemostusedsensorsingeneralaudiencephotography. Table3:Nominalsizeofphotographicsensors [zoom...]Info AccueilNouvellepageInformationssurlecours(ouvrirdansunenouvellefenêtre)TransportandconversionofthechargeDefects