Canon imageRUNNER ADVANCE 8105 Series Service Manual page 554

Uneven density correction by 2D shading
To correct uneven image density caused by uneven potential on the surface of the Drum.
MEMO:
This machine performs two dimensional shading which replaces uneven potential of
the Photosensitive Drum to the exposure amount to correct. (Default: two dimensional
shading is disabled.) As the data of Drum's uneven potential, the data measured at
the shipment of the Drum is used. Therefore, as the life of the Photosensitive Drum
advances, it gets deteriorated, so the uneven potential becomes different from the one
at the shipment of the Drum. Although the uneven potential of the Drum is changed
due to the deterioration, the data can be corrected per horizontal/vertical scanning
direction line by outputting a test pattern image with the following procedure.
CAUTION:
This adjustment is executed when the preferred image is not output even if the
Primary Charging Wire height adjustment and secure watermark adjustment * are
performed.
* Secure watermark adjustment: Function Settings>Common>Print Settings>Secure
Watermark Settings>Adjust Background/Character Contrast
1) Check that the two dimensional shading is enabled.
COPIER>OPTION>IMG-LSR>2D-SHADE 1: Enabled
2) Turn OFF and then ON the main power switch.
CAUTION:
Be sure to turn OFF and then ON the main power switch after step 1. Uneven density
may be reduced by the two dimensional shading correction at the startup.
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Troubleshooting > Image Faults > Uneven density correction by 2D shading
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Troubleshooting > Image Faults > Uneven density correction by 2D shading
3) Output a halftone image with the following conditions and check if uneven density occurs.
COPIER>TEST>PG>TYPE 6
Select the cassette which the following paper is set: COPIER>TEST>PG>PG-PICK A3
(LDR) or larger.
When uneven density is seen: Go to step 4.
When uneven density is not seen: Procedure is ended.
4) Output a test pattern for two dimensional shading.
COPIER>FUNCTION>2D-SHADE>SHD-P1
4-1) Set the cassette.Select the cassette which A3 (LDR) or larger paper is set.
Select "SHD-P1" and cassette using "numeric keypad".
4-2) Output 3 sheets of the test pattern.
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F-6-8 F-6-8
F-6-9 F-6-9
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