Patch Detection; Operation Description; Led Light Intensity Correction; Drum Base Correction - Canon imageRUNNER ADVANCE 8105 Series Service Manual

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Technology > Image Formation System > Controls > Image Stabilization Control
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Patch Detection

Toner density is detected by detection of the patch created on the Drum with the Patch
Sensor.
Parts configuration
The Patch Sensor consists of the light-emitting part (LED) and the light-receiving part.
• Light-emitting part (LED): to emit light to the patch image (PATCH_VOP_ANALOG signal)
Reflected light detection part: to receive light reflected from patch image
•
(PATCH_LED_ASW_IN signal)
Patch Sensor
PATCH_VOP_ANALOG
PATCH_LED_ASW_IN
DC Controller PCB
PATCH_LED_ON

Operation description

1) LED light intensity correction

Reflected light is detected by the Patch Sensor by changing LED light intensity (input
voltage) (6 points) while rotating the Drum to calculate LED light intensity characteristics.
LED light intensity (input voltage) is calculated by the LED light intensity characteristics,
which become the target reflected light intensity.

2) Drum base correction

LED is emitted with the light intensity (input voltage) determined by the LED light intensity
correction to measure reflected light intensity for a rotation of the Drum. Using the Drum HP
Sensor as a reference, the reflected light intensity and the position on the Drum are saved
in the memory on the DC Controller PCB. The patch density is calculated with this drum
base correction value.
3) A patch pattern is created on the DC Controller PCB to form the patch pattern on the Drum.
The patch pattern differs according to the control to be executed (D-max control/D-half
control).
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Technology > Image Formation System > Controls > Image Stabilization Control
<Patch image at D-max control>
Patch
image
<Patch image at D-half control>
Photosensitive Drum
F-2-104 F-2-104
Drum rotation direction
Halftone patch
Approx
(for correction of halftone)
20 mm
Approx 32 mm
< Patch image >
Drum rotation direction
14 patches x 9 types (dither pattern)
2-80
Shadow patch
(for correction of
solid density)
Approx 32 mm
F-2-105 F-2-105
F-2-106 F-2-106
2-80