Developing Device Notched Blade Toner Leakage
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Solution Overview
Problem
Existing developing devices in image forming apparatuses, such as laser printers, experience toner leakage due to uneven pressure distribution on the toner thin layer-forming blade and seal members, leading to inefficiencies in toner containment.
Innovation Solution
A developing device design featuring a layer-thickness regulating member with a thin plate-like shape, a projection member with multiple pressure contact portions, and a notched portion to reduce pressure on the second pressure contact portion, combined with side and blade seals to prevent toner leakage from the developing agent carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the projection is provided over the entire longitudinal width of the toner thin layer-forming blade, then the layer thickness of toner can be regulated uniformly, but the both longitudinal end portions of the blade are more abraded than the center portion due to higher pressure applied
Solution Approach 1:
The invention applies local quality by creating a notched portion at the longitudinal end of the toner thin layer-forming blade. This notch removes material from the high-stress end region, reducing the blade's moment of inertia and flexibility at that location. Consequently, the end portion experiences reduced abrasion during operation while the central region maintains sufficient thickness for proper toner layer formation, resolving the contradiction between uniform layer thickness and blade durability
2Reliability
If the first seal member is disposed on the upstream side of the rotation direction with respect to the abutting position of the projection, then the seal member can prevent toner leakage, but toner leakage occurs from the portion between the toner thin layer-forming blade and the first seal member
Solution Approach 1:
The invention applies preliminary action by positioning the notched portion at the longitudinal end of the toner thin layer-forming blade upstream relative to the seal member location. This preliminary structural modification creates a geometry that prevents toner from accumulating or leaking between the blade and seal member, addressing the leakage issue before it can occur during the developing operation
3Strength
If the lateral end portions of the leaf-spring member are formed narrower, then the pressure applied to the end portions is reduced, but toner leakage still occurs from the portion between the leaf-spring member and the side seals
Solution Approach 1:
The invention applies segmentation by introducing a notched portion that divides the leaf-spring member structure into distinct regions. The notch creates a geometric feature that prevents toner from migrating to the gap between the blade and side seal, thereby eliminating the leakage path while maintaining the narrowed end geometry for reduced abrasion
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
Effectively prevents toner leakage by reducing pressure differences and ensuring secure toner containment between the layer-thickness regulating member and seal members, enhancing the reliability of the image forming process.
Implementation Method 1
a projection member that comes into pressure-contact with a surface of the developing agent carrier to form a thin layer of the developing agent on the surface of the developing agent carrier
Implementation Method 2
a leakage preventing member that is arranged at each of both longitudinal end portions of the casing to prevent the developing agent from leaking out of the casing
Data Source
AI summary
A layer-thickness regulating member may include a thin plate member and a projection member. The projection member includes a first pressure contact portion that comes into pressure-contact with each of seal areas, a second pressure contact portion that comes into pressure-contact with each of side end areas, and a third pressure contact portion that comes into pressure-contact with a central area. A notched portion is formed at a position of the distal end of the thin plate member where each of the second pressure contact portions is formed, by cutting the thin plate member from an end edge of the distal end toward a downstream side of the rotation direction of the developing agent carrier.