Developing Device Velocity Ratio Control for Toner Charging Degradation
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Solution Overview
Problem
Image forming apparatuses experience deterioration in printing quality due to decreased toner charging and increased optical density as the number of printed copies increases, leading to blurring and scattering issues.
Innovation Solution
An image forming apparatus with a controller that adjusts the velocity ratio of the developing device to the photoconductive medium based on the accumulated number of printed copies, decreasing the velocity ratio to maintain optical density and prevent scattering by controlling the velocity of the developing device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a cleaning blade is used to remove toner remainder from the photoconductive medium, then toner removal is improved, but abrasion on the photoconductive medium film increases causing OD darkening and image quality deterioration
Solution Approach 1:
The patent changes the velocity ratio parameter between the developing device and photoconductive medium dynamically. By decreasing the velocity ratio as the number of printed copies increases, the system compensates for carrier and toner charging degradation without requiring aggressive cleaning that causes abrasion. This parameter adjustment maintains optimal developing performance throughout the life cycle.
Solution Approach 2:
The patent implements dynamic velocity ratio adjustment based on the accumulated number of printed copies. The system transitions from a fixed velocity ratio to a variable one that adapts to degradation conditions, allowing the developing device to rotate at different speeds relative to the photoconductive medium at different stages of its life cycle.
2Productivity
If the number of printed copies increases, then productivity is improved, but carrier and toner charging decreases leading to OD increase and image quality deterioration
Solution Approach 1:
The patent uses feedback from the accumulated number of printed copies to adjust the velocity ratio. The controller monitors the copy count and dynamically modifies the developing device velocity accordingly, creating a closed-loop control system that compensates for degradation effects and maintains consistent image quality throughout the device life cycle.
Solution Approach 2:
The system changes the velocity ratio parameter in response to increasing copy counts. By decreasing the velocity ratio as productivity increases, the system compensates for the natural degradation of carrier and toner charging, thereby maintaining reliable image quality despite higher productivity levels.
3Manufacturing precision
If the velocity ratio of the developing device is decreased, then optical density is maintained within a predetermined range, but developing efficiency may be reduced
Solution Approach 1:
The patent applies dynamic velocity ratio adjustment rather than using a fixed low velocity ratio. The system adjusts the velocity ratio dynamically based on the number of printed copies, maintaining optimal developing efficiency at each stage while ensuring optical density remains within the predetermined range. This dynamic approach prevents permanent efficiency loss.
Data Source
AI summary
An image forming apparatus and a method to control a velocity ratio thereof. The image forming apparatus includes a developing device to rotate opposite a photoconductive medium and to supply the photoconductive medium with a developer, and a controller to control a velocity ratio of the developing device to the photoconductive medium according to an accumulated number of printed copies.