Developing Roller Speed and Bias Control for Press Fogging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image forming apparatuses face challenges in suppressing press fogging, which occurs when toner moves from the developing roller to non-image areas of the photosensitive member, especially at room temperature and low humidity conditions.
Innovation Solution
An image forming apparatus with a controller that adjusts the peripheral speed ratio and developing bias of the developing roller, applying a low developing bias for a predetermined time during non-developing and switching to a high bias and high speed after the non-developing phase, ensuring the toner is effectively transferred to the image area without fogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low developing bias is applied during non-developing to suppress press fogging, then press fogging is reduced, but the developing roller may not effectively supply developer to the electrostatic latent image when developing
Solution Approach 1:
The patent applies dynamic adjustment of the developing bias voltage based on the operational state. During non-developing, a low developing bias is applied to suppress press fogging, while during developing, the bias is increased to ensure effective developer supply. This dynamic switching resolves the contradiction by adapting the bias level to the current operational phase, preventing press fogging when not developing while maintaining developer supply efficiency when developing is required
Solution Approach 2:
The patent changes the electrical parameter (developing bias voltage) based on the operational state. By switching between low bias during non-developing and high bias during developing, the system resolves the contradiction between suppressing press fogging and maintaining effective developer supply. The parameter change allows the same developing roller to serve dual purposes without compromising either function
2Object-affected harmful factors
If the peripheral speed ratio of the developing roller to the photosensitive member is set to a small ratio during non-developing, then press fogging is suppressed, but the transfer efficiency of developer to the sheet may be reduced
Solution Approach 1:
The patent dynamically adjusts the peripheral speed ratio of the developing roller based on the operational phase. During non-developing, a small peripheral speed ratio is maintained to suppress press fogging by reducing toner movement. During developing, the peripheral speed ratio is increased to ensure efficient developer transfer to the photosensitive member and subsequent transfer to the sheet. This dynamic speed adjustment resolves the contradiction between fogging suppression and transfer efficiency
Solution Approach 2:
The patent prepares the developing roller by maintaining a small peripheral speed ratio during non-developing periods before developing operations. This preliminary state preparation prevents press fogging in advance, and when developing is required, the system transitions to a higher speed ratio to ensure efficient developer supply and transfer, thus resolving the efficiency concern
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively suppresses press fogging by controlling the developing bias and speed ratio, ensuring high image quality by preventing toner movement to non-image areas, thereby maintaining image integrity across varying environmental conditions.
Implementation Method 1
a developing bias applying circuit configured to selectively apply a low developing bias or high developing bias to the developing roller
Data Source
AI summary
An image forming apparatus is provided with: a controller capable of changing a developing bias, which is to be applied to a developing roller configured to carry developer thereon; a peripheral speed ratio of a developing roller to a photosensitive member; a control method by the controller, and a program for operating the controller. A configuration is provided where the developing roller makes contact with the photosensitive member when a developing bias is made to be lower during the non-developing than during a developing phase. The configuration can suppress press fogging at room temperature and low humidity conditions.