Canon imageRUNNER ADVANCE C255 Series, Service Manual, Page: 78 / 987

• When it is determined necessary based on the predicted value for temperature inside the machine (according to the usage
environment and continuous print state).
Control description
Color displacement correction control based on patch pattern
1. The Main Controller PCB forms the patch pattern of each color on the ITB.
2. The DC Controller PCB scans this patch pattern using the Registration Patch Sensor Unit (Front) (UN31) and
Registration Patch Sensor Unit (Rear) (UN32) to detect the amount of color displacement compared to the reference
color (Y).
3. Based on the above-mentioned detection result, the DC Controller PCB executes correction according to the degree of
color displacement.
Color displacement correction control based on temperature prediction
1. The degree of color displacement is measured based on the operating condition (mainly temperature).
2. The exposure timing for M/C/Bk is adjusted based on Y.
3. Color displacement correction is performed based on the above patch patterns.
Type of control Correction description
Correction in horizon-
tal scanning direction Write start correction Write-start timing in horizontal scanning direction is changed.
Entire-area magnification ratio
correction Pixels in horizontal scanning direction is increased/reduced (at the
both edges of the image)
Correction in vertical
scanning direction Write start correction Write-start timing in vertical scanning direction is changed.
Image skew correction Image data is corrected.
Toner Supply Assembly
■ Overview
Toner is supplied from the Toner Container to the Developing Assembly. The toner level in the Toner Container is detected at
the same time.
Hopper Unit
Bottle Rotation Sensor
(Y,M,C,Bk)
(PS6,7,8,9)
ATR Sensor
(Y,M,C,Bk)
(UN34,35,36,37)
Toner Container
Toner Feed Screw
Developer Feed Screw B
Developer Feed Screw A
Toner Log Connector
(Y,M,C,Bk)
(UN38,39,40,41)
Parts name Role
Hopper Unit Toner is supplied from the Toner Container to the Developing As-
sembly.
Toner Feed Screw Toner is supplied from the Hopper Unit to the Developing Assembly.
2. Technology
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