Developing Roller Reverse Rotation for Toner Clump Prevention
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Solution Overview
Problem
In image forming apparatuses using a two-component developing method, residual toner accumulates on the regulation member and internal walls of the developing container, leading to defective images due to toner clumps falling onto the developing roller and causing vertical line defects.
Innovation Solution
An image forming apparatus with a toner collecting mode that reverses the rotation direction of the developing roller and magnetic roller to collect residual toner, using a controller to switch between printing and toner collecting modes, ensuring toner is not transferred to the image carrier and is instead collected back to the agitation portion, reducing accumulation on the regulation member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the regulation member regulates the layer thickness of the developer on the magnetic roller, then the uniformity of developer layer is improved, but toner is scraped off and accumulates on the regulation member causing defective images
Solution Approach 1:
The patent applies reverse rotation of the developing roller and magnetic roller to collect accumulated toner from the regulation member. By rotating the rollers in the opposite direction, toner that has accumulated on the regulation member is scraped off and returned to the developer container, preventing defective images while maintaining the regulatory function of the member.
Solution Approach 2:
The patent recovers toner that would otherwise be wasted or cause defects. Through reverse rotation, toner accumulated on the regulation member is collected and returned to the developer container, making it available for reuse in subsequent image formation operations.
2Productivity
If the developing roller rotates continuously to convey toner to the photosensitive member, then image formation productivity is improved, but residual toner accumulates on the internal wall of the developing container
Solution Approach 1:
The patent implements periodic reverse rotation of the developing roller and magnetic roller during or between image formation operations. This periodic action collects residual toner from the internal walls of the developing container and returns it to the developer container, preventing toner clump formation while maintaining continuous productivity.
Solution Approach 2:
The patent maintains continuous image formation productivity by implementing toner collection during or between printing operations rather than stopping production. The reverse rotation occurs in a manner that does not interrupt the overall image formation process, ensuring continuous useful action.
3Reliability
If toner is fed from the developing roller to the photosensitive member, then image development is improved, but floating toner adheres to the regulation member and causes vertical line defects
Solution Approach 1:
The patent converts the harmful effect of floating toner adhesion into a beneficial collection mechanism. By implementing reverse rotation, the toner that would cause vertical line defects is instead collected and returned to the developer container, transforming a quality problem into a resource recovery opportunity.
Solution Approach 2:
The patent uses reverse rotation of the rollers to counteract the forward motion that causes toner adhesion problems. This inversion of the rotation direction during collection mode allows accumulated toner to be removed from the regulation member and returned to the developer container.
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
Significantly reduces the frequency of defective images and the amount of toner accumulation on the regulation member, maintaining image quality by effectively preventing toner clumps from forming and adhering to the developing roller.
Implementation Method 1
a magnetic roller that is provided with an internal magnet which allows the magnetic roller to carry a developer containing a toner and a magnetic carrier on its surface as a magnetic brush
Implementation Method 2
a developing roller that is disposed facing a photosensitive member and the magnetic roller, that carries on its surface the toner contained in the magnetic brush that is conveyed by the magnetic roller, and that feeds the carried toner to the photosensitive member
Data Source
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AI summary
An image forming apparatus (1) includes a controller (160, 132) that controls rotational driving of a magnetic roller (21) and rotational driving of a developing roller (20). The controller (160, 132) is capable of performing a toner collecting mode when no image formation is performed. In the toner collecting mode, the magnetic roller (21) and the developing roller (20) are intermittently rotated in a direction reverse to a direction in which the magnetic roller 21 and the developing roller (20) are rotated during image formation, then the magnetic roller (21) is made to rotate in a forward direction, and then, the magnetic roller (21) is rotated in a backward direction.