Chapter 55-155.3.6.7 Shading Correction 0006-5938iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N // iR4570N / iR2230 / / / iR3530 /The machine executes this correction for every scan made in main shadingunit. It measures the density of the standard white plate, and compares theresult against the target value stored in the shading correction circuit; the dif-ference between the two will be held as the shading correction value for usein correcting variation among CCD pixels when scanning the original, thusevening out the density levels of the image.F-5-285.4 Parts Replacement Procedure5.4.1 Copyboard glass5.4.1.1 Removing the Copyboard Glass 0006-9714iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N // iR4570N / iR2230 / / / iR3530 /1) Open the copyboard cover (or ADF).2) Remove the 2 screws [1], and detach the glass retainer [2]; then, detachthe copyboard glass [3].F-5-29When removing the copyboard glass, take care not to touch the following:- glass surface- standard white plateThe presence of dirt can cause white/black lines in the images. If dirt isfound, clean it with lint-free paper moistened with alcohol.F-5-305.4.1.2 Removing the ADF Reading Glass 0006-9730iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N // iR4570N / iR2230 / / / iR3530 /1) Open the copyboard glass (or ADF).2) Remove the 2 screws [1], and detach the glass retainer [2].3) Remove the ADF reading glass [3].F-5-31When removing the ADF reading glass, take care not to touch the glass sur-face.The presence of dirt can cause white/black lines in the images. If dirt isfound, be sure to clean it using lint-free paper moistened with alcohol.5.4.2 Reader Controller PCB5.4.2.1 Before Replacing the Reader Controller PCB 0007-0740iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N /CCD outputOriginal densityStandard white plateCharacteristics beforeTarget valueMeasurementCharacteristics after coWhite
