Canon MF8580Cdw Service Manual page 54

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Technical Overview > Image Formation System > Controls > Image stabilization control
● Image density correction control (D-max control)
This control is to stabilize the print image density.
The DC controller PCB triggers D-max control under the pre-defined conditions.
1. Measure the density detection patterns for each color on the ITB.
2. To optimize the density of the measured patterns, control the primary charging bias and the
developing bias.
The image density correction control is triggered under the conditions below.
• In the case of Menu > Adjustment/Cleaning > Auto Adjustment Settings > Auto Adjustment
Image Regularly: OFF (default)
1) At power ON (When the environmental change is great compared with the condition
before turning OFF the power (more than +/-10 degC))
2) When replacing the Toner Cartridge
3) When the environmental change is great while not getting into the sleep state (more
than +/-5 degC)
4) After printing the specified number of sheet (every 500 sheets)
5) After printing or after 300 min. since the execution of the image density correction
6) At recovery from the sleep state (When the environmental change is great compared
with the condition before getting into the sleep state (more than +/-10 degC))
7) When the user commands execution of the calibration
• In the case of Menu > Adjustment/Cleaning > Auto Adjustment Settings > Auto Adjustment
Image Regularly: ON, the operation of (1) and (6) mentioned in the above conditions will be
as follow:
1)' Must execute at power ON
6)' Must execute at recovery from the 8-hour (or longer) sleep state
● Image gradation correction control (D-half control)
This control is to correct the gradation by the main controller PCB based on the half-tone
density measured by the DC controller PCB.
Upon D-max control completed, the DC controller PCB and the main controller PCB enter the
following steps of D-half control.
1. The DC controller PCB measures the density detection patterns on the ITB by applying the
primary charging bias and the developing bias optimized through D-max control to send the
density data to the main controller PCB.
2. The main controller PCB corrects gradation based on the density data to reproduce the
ideal half-tone images.
2 Technical Overview > Image Formation System > Controls > Image stabilization control
● Color displacement control
This control is to correct color displacement due to variability of the laser units or toner
cartridges.
The following displacements are corrected through this control.
• Horizontal scanning start position
• Horizontal scanning magnification
• Vertical scanning start position
The DC controller PCB controls the color displacement/density sensor and the color
displacement sensor under the conditions below.
• In the case of Menu > Adjustment/Cleaning > Auto Adjustment Settings > Correct Color
Mismatch when turned ON: OFF (default)
1) When completing the first job after power ON
2) When replacing the Toner Cartridge
3) After printing the specified number of sheet (every 150 sheets)
4) After the specified time has passed
• MF8200 Series: only twice (100 min, and 300 min)
• MF8500 Series: 60 min, after that every 240 min
5) When completing the first job after recovering from the 8-hour (or longer) sleep state
6) When the user commands execution of the color displacement correction
• In the case of Menu > Adjustment/Cleaning > Auto Adjustment Settings > Correct Color
Mismatch when turned ON: ON, the operation of (1) and (5) mentioned in the above
conditions will be as follow:
1)' At power ON, execute before executing a job
5)' At recovery from the 8-hour (or longer) sleep state, execute before executing a job
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