Co-rotating Developing Roller Bias Control for Ghost Reduction
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Solution Overview
Problem
In co-rotating developing assemblies, development ghost and solid image compliance defects occur due to non-uniform toner supply and weak mechanical stripping, leading to image density inconsistencies and reduced lifespan.
Innovation Solution
An image forming apparatus with a developer bearing member and a supply member that move in the same direction, where the developing bias and supply bias are controlled to gradually increase the stripping force using electrostatic forces, ensuring consistent toner supply and reducing mechanical rubbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the supply roller and developing roller rotate in the same direction (co-rotating), then the mechanical structure is simplified, but the mechanical stripping action becomes weak causing development ghost
Solution Approach 1:
The patent replaces the mechanical stripping action with electrostatic force. By applying a supply bias to the supply roller that is higher in absolute value than the developing bias on the developing roller, electrostatic attraction is generated to strip residual toner from the developing roller surface, eliminating development ghost without requiring complex mechanical structures.
Solution Approach 2:
The patent changes the electrical parameter (bias voltage) relationship between the supply roller and developing roller. Specifically, it sets the supply bias to have a higher absolute value than the developing bias, creating an electrostatic potential difference that enables effective toner stripping and supply in the co-rotating configuration.
2Reliability
If the supply roller increases mechanical rubbing to improve stripping, then development ghost is reduced, but toner degradation increases
Solution Approach 1:
The patent substitutes electrostatic force for mechanical rubbing action. By using electrostatic attraction generated through bias voltage control, the supply roller can strip residual toner and supply fresh toner without the need for increased mechanical friction, thereby preventing toner degradation while eliminating development ghost.
3Manufacturing precision
If bias control is applied to reduce development ghost, then image density uniformity is improved, but solid image compliance defects may occur
Solution Approach 1:
The patent optimizes the bias voltage parameters by setting the supply bias to have a higher absolute value than the developing bias. This parameter configuration creates sufficient electrostatic attraction for effective toner stripping and supply, achieving both uniform image density and solid image compliance without causing defects.
Solution Approach 2:
The patent implements bias control that responds to the co-rotating configuration feedback. By detecting the rotational direction relationship between supply and developing rollers, the system adjusts the bias voltages appropriately to ensure the supply bias exceeds the developing bias in absolute value, maintaining optimal performance across different operating conditions.
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 approach reduces development ghost and prevents solid image compliance defects, achieving high image quality and extending the lifespan of the developing assembly by maintaining consistent toner supply and minimizing toner degradation.
Implementation Method 1
the biases applied respectively to a developing roller and a supply roller are controlled so that a biasing force which acts on a developer in a region of contact between the developing roller and the supply roller, in a direction from the supply roller toward the developing roller, increases gradually
Implementation Method 2
toner is supplied to the developing roller while being triboelectrically charged by mechanical rubbing between the supply roller and the developing roller
Data Source
AI summary
An image forming operation for forming an image on one recording material includes a developing bias application unit applying a developing bias to a developer bearing member and a supply bias application unit applying a supply bias to a developer supply member. At the start of image formation, an absolute value of the developing bias is greater than an absolute value of the supply bias, and in a center or latter half of the image formation period, the developing bias and the supply bias have equal potential, and then the absolute value of the developing bias becomes smaller than the absolute value of the supply bias, until the end of image formation.