Developing Device Opposite-Rotating Foam Roller Prevents White Streaks
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Solution Overview
Problem
Existing cleanerless image forming apparatuses face challenges in maintaining image quality, particularly with high image area ratios, due to foreign matter accumulation and toner shortages at the contact positions between the supply and developing rollers, leading to defects like white streaks.
Innovation Solution
The supply roller is designed with a foam layer surface featuring closed independent bubbles smaller than 300 μm in diameter, rotating opposite the developing roller, and positioned to allow foreign matter to accumulate away from the toner container, with controlled surface velocity and contact depth to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the supply roller rotates in the same direction as the developing roller, then the structure is simple, but foreign matter accumulates at the contact position causing image defects
Solution Approach 1:
The supply roller is configured to rotate in the opposite direction to the developing roller at the contact position. This inversion of the conventional same-direction rotation prevents foreign matter from accumulating at the contact interface, thereby eliminating image defects like white streaks while maintaining structural simplicity
2Ease of manufacture
If the foam layer has large cells, then it is easier to manufacture, but toner supply becomes inconsistent causing white streaks
Solution Approach 1:
The foam layer cell diameter is precisely controlled to be within the range of 50-300 μm. This parameter optimization ensures sufficient toner supply consistency to prevent white streaks, while remaining practically manufacturable by adjusting foam generation conditions such as surfactant concentration and mixing speed
3Quantity of substance
If the supply roller contacts deeply into the toner container, then toner supply is sufficient, but foreign matter accumulates leading to image defects
Solution Approach 1:
By reversing the rotation direction of the supply roller relative to the developing roller, the configuration prevents foreign matter from being carried to the contact position even when the roller penetrates deeply into the toner container, thus maintaining sufficient toner supply without image defects
4Ease of manufacture
If the foam layer has open connected cells, then it is easier to produce, but foreign matter accumulates causing white streaks
Solution Approach 1:
The foam layer is designed with closed independent cells having diameters of 50-300 μm. This structural parameter change prevents foreign matter from being trapped and attached, eliminating white streaks while maintaining ease of production through controlled foam generation parameters
Data Source
AI summary
A developing device includes a developer bearer, a developer container, a supply rotator, and a layer thickness regulator. The developer bearer is rotatable in a first direction to supply developer to a latent image bearer. The developer container contains the developer to be supplied to the developer bearer. The supply rotator supplies the developer in the developer container to the developer bearer at a contact position at which the supply rotator contacts the developer bearer. The layer thickness regulator forms a layer of the developer having a regulated thickness on the developer bearer. The developer bearer collects residual toner from the latent image bearer. The supply rotator rotates in a second direction opposite the first direction of the developer bearer at the contact position. The supply rotator has a surface of a foam layer including a single foam cell having a diameter smaller than 300 μm.