Developing Roller Lubricant Zoning for Toner Fogging
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the non-magnetic one component contact developing system faces issues with toner adhering to non-image forming regions (fogging) due to low charging performance or incorrect toner polarity, leading to banding images and vertical streaks, as existing solutions like developer layer thickness regulating members and lubricants either reduce coating agent retention or cause frictional issues.
Innovation Solution
A developing roller configuration with distinct regions for toner coating and non-coating areas, where the toner coating region has a lubricant with a larger particle size than the surface roughness and the toner non-coating region has a lubricant with a smaller particle size, ensuring increased retention of the coating agent in the non-coating area and quick disappearance in the coating area, thereby reducing friction and preventing banding and streaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a developer layer thickness regulating member is provided on the developing roller to prevent fogging, then toner charging performance is improved, but the coating agent is mechanically taken off by the sealing member, reducing its retention
Solution Approach 1:
The patent applies different lubricant particle sizes to different regions of the developing roller: smaller particle size lubricant in the toner non-coating region (where sealing member contact occurs) to prevent mechanical removal, and larger particle size lubricant in the toner coating region for effective toner charging. This local differentiation resolves the contradiction by optimizing each region's properties for its specific function.
2Object-affected harmful factors
If a coating agent is applied to the developing roller to reduce friction, then banding images are prevented, but the coating agent remains in the toner coating region causing vertical streaks
Solution Approach 1:
The patent uses different lubricant particle sizes in different regions: smaller particle size in the toner non-coating region to maintain friction reduction and prevent banding, while larger particle size in the toner coating region allows quick disappearance during operation, preventing vertical streaks. This spatial differentiation of lubricant properties resolves the harmful effects in各自 regions.
3Manufacturing precision
If the surface roughness of the developing roller is reduced to achieve thin toner layer, then toner charging performance is improved, but friction increases causing stick-slip phenomenon
Solution Approach 1:
The patent introduces a lubricant coating as an intermediary substance between the developing roller surface and the toner/sealing member. The lubricant particles fill the surface roughness valleys and provide a low-friction interface, mediating the interaction between the smooth roller surface and external elements. This resolves the high friction issue while maintaining the thin toner layer required for good charging performance.
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 configuration effectively prevents banding images by maintaining coating agent retention in the non-coating region and ensuring its quick disappearance in the coating region, reducing friction and preventing image defects like banding and vertical streaks.
Implementation Method 1
a lubricant coating formed on a developing roller in a non-magnetic one component contact developing system
Implementation Method 2
charges the surface of an image bearing member with charging portion, and irradiates the photosensitive member with light corresponding to image data, to thereby form an electrostatic image
Data Source
AI summary
A developing apparatus includes: a developing roller; a frame configured to support the developing roller at each of two end portions of the developing roller in a longitudinal direction of the developing roller; and a sealing member configured to seal a space between the frame and each of the two end portions of the developing roller. A first lubricant having an average particle size smaller than a predetermined surface roughness Ra is applied to a first region that is located at each end portion of the developing roller in the longitudinal direction and is in contact with the sealing member. A second lubricant having an average particle size larger than the surface roughness Ra is applied to a second region that is located on an inner side of the first region in the longitudinal direction and is separated from the sealing member and has the surface roughness Ra.