Developing Device Seal Structure for Toner Scatter Control
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Solution Overview
Problem
Existing developing devices experience toner scatter from the axial end portions of the developer layer, which is not effectively addressed by simple seal portions, leading to leakage and reduced suction efficiency.
Innovation Solution
Incorporating a first seal portion that covers the radial outer side of the axial end portion where the developer layer is not formed and a second seal portion that extends inward in the axial direction to cover the outer side of the axial end portion, reducing toner scatter by preventing airborne toner from escaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple seal portion is used to cover the axial end portion of the development roller, then the structure is simple and easy to manufacture, but toner scatter from the axial end portions of the developer layer is not effectively prevented
Solution Approach 1:
The seal portion is divided into two distinct segments: a first seal portion covering the axial end portion of the development roller, and a second seal portion covering the axial end portion of the developer layer. This segmentation allows each seal portion to address specific areas where toner scatter occurs, effectively preventing toner escape while maintaining a relatively simple overall structure.
Solution Approach 2:
The second seal portion extends in the axial direction beyond the first seal portion, adding an axial dimension to the sealing structure. This extension allows the seal to cover not only the roller's axial end but also the developer layer's axial end, which is a different spatial dimension, thereby effectively preventing toner scatter without significantly complicating the structure.
2Object-affected harmful factors
If the seal portion extends further in the axial direction to cover the developer layer end, then toner scatter is reduced, but the device complexity increases
Solution Approach 1:
The first and second seal portions are merged into a single integrated seal member that performs both sealing functions. This merging approach prevents toner scatter effectively by covering both the roller end and developer layer end, while avoiding the complexity of separate, independent sealing mechanisms.
Solution Approach 2:
The seal portion has different local qualities: the first seal portion covers the roller's axial end area, while the second seal portion extends to cover the developer layer's axial end area. This local differentiation allows each part of the seal to address specific toner scatter issues at different locations, achieving effective toner containment without requiring a uniformly complex structure throughout.
Data Source
AI summary
A developing device includes: a development roller that has a circumferential surface on which a developer layer is formed at a portion facing an image carrier; a first seal portion that covers an outer side, in a radial direction, of an axial end portion of the development roller where the developer layer is not formed at the portion facing the image carrier; and a second seal portion that extends inward in an axial direction from the first seal portion, and that covers an outer side, in the radial direction, of an axial end portion of the developer layer.