Developing Device Toner Charging Stability
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Solution Overview
Problem
Existing image forming apparatuses using two-component developers face challenges in stabilizing toner charging ability and preventing uneven toner concentration due to increased shearing stress during developer conveyance, which affects the flowability and longevity of image formation.
Innovation Solution
The development of a developing device with multiple conveyance paths and members that allow for controlled circulation and agitation of the two-component developer, including a toner supply system that ensures new toner is added only to developers with lowered toner concentration, reducing stress and enhancing miscibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fins are provided on the screw member to enhance miscibility and agitation, then the charge impart ability is improved, but the shearing stress on the developer increases causing external additive to be buried and flowability to reduce
Solution Approach 1:
The patent removes the fins from the screw member, extracting the harmful element that causes excessive shearing stress. The screw member is used only for conveyance without agitation fins, thereby eliminating the source of buried additives and reduced flowability while maintaining sufficient charge impart ability through alternative means.
Solution Approach 2:
The patent introduces a separate agitation mechanism using a developer holder with irregularities that act as an intermediary for providing necessary agitation without the harmful fins on the screw member. This mediator provides the needed mixing and charge impart ability while avoiding excessive shearing stress.
2Productivity
If the developer is conveyed quickly to meet high-speed requirements, then productivity is improved, but the stress on the developer increases causing external additive to be buried
Solution Approach 1:
The patent removes the source of excessive stress by eliminating fins from the screw member. This allows quick conveyance without the harmful shearing stress that would otherwise bury external additives, thus maintaining both high productivity and developer integrity.
3Reliability
If supplementary toner is dispersed into the developer to maintain charge, then the toner charging stability is improved, but the miscibility may be affected by stress on the developer
Solution Approach 1:
The patent removes fins from the screw member, eliminating the source of excessive stress that would harm miscibility. This allows supplementary toner to be dispersed effectively without compromising the developer's composition stability, thereby maintaining both charging stability and miscibility.
Solution Approach 2:
The patent uses the developer holder with irregularities as an intermediary mechanism to provide gentle mixing and charge impart ability. This mediator ensures supplementary toner is dispersed uniformly without creating excessive stress that would affect miscibility, thus maintaining composition stability.
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 stabilizes toner charging, prevents uneven toner concentration, and ensures consistent image formation over time by reducing stress on the developer and improving miscibility between toner and carrier.
Implementation Method 1
a developer drawing member provided in the developer drawing and conveyance path in a freely rotatable manner for simultaneously agitating and conveying the two-component developer in one direction
Implementation Method 2
a developer drawing member provided in the developer drawing and conveyance path in a freely rotatable manner for simultaneously agitating and conveying the two-component developer in one direction
Implementation Method 3
The charged toner is supplied to a surface of a developer holder such as a developing roller. The toner supplied to the developing roller is transferred to an electrostatic latent image formed on a photoconductor drum by electrostatic attraction.
Implementation Method 4
a screw member having an agitating vane on a rotation axis and plate-like members (fins) attached to spaces in the agitating vane for agitating and conveying the developer
Data Source
AI summary
A developing device comprises a first and a second developer conveyance path; a first conveyance member; a second conveyance member; and, a developing roller. A developer collection path guides the developer left on a surface of the developing roller in a direction away from the first developer conveyance path. A third conveyance member is provided in a third developer conveyance path. A toner supply port supplies new toner to the third developer conveyance path. A developer drawing and conveyance path guides the developer supplied with the new toner to the second developer conveyance path. A developer drawing member is provided in the developer drawing and conveyance path for simultaneously agitating and conveying the developer.