Development Roller Sleeve Recesses for Toner Charge Stability

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Solution Overview

Problem

Existing developing devices for image forming apparatuses face challenges in maintaining stable toner charge and preventing toner congestion due to the design of the development roller's surface features, leading to issues with image quality and durability.

Innovation Solution

The developing device incorporates a development roller with a sleeve featuring elongated recesses arranged in predetermined intervals, which allows for efficient conveyance and charging of the toner, preventing congestion and maintaining a stable charge, while the layer-thickness limiting member ensures optimal toner supply to the photosensitive drum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the development roller uses a conventional surface design with recesses, then the device structure is simple, but toner congestion occurs and charge stability deteriorates

Engineering Contradiction:

Improvetoner charge stabilityVSAvoidsleeve structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sleeve surface is segmented into multiple recesses that are spatially separated rather than continuously connected. Each recess is isolated from adjacent recesses by raised portions, creating discrete zones for toner conveyance that prevent congestion while maintaining structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sleeve surface exhibits local quality variations through the strategic placement of recesses at specific intervals rather than uniform distribution. This localized structuring optimizes toner flow paths in critical areas while preventing congestion zones, improving charge stability without requiring complete surface redesign.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the recesses are arranged to connect at ends, then manufacturing is easier, but toner scattering occurs and image quality deteriorates

Engineering Contradiction:

Improvesleeve manufacturing easeVSAvoidtoner conveyance precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The recesses are designed as isolated segments rather than continuous connected structures. This segmentation prevents toner from scattering between adjacent recesses while maintaining straightforward manufacturing processes through standardized recess patterns that can be replicated independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection portions between recesses are extracted or removed, creating distinct separated zones. This extraction prevents the harmful effect of toner scattering that would occur through continuous connections, while the individual recesses can still be manufactured using standard techniques.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If the sleeve rotates around the fixed magnet, then toner supply to photosensitive drum is improved, but toner congestion occurs without proper spacing

Engineering Contradiction:

Improvetoner supply efficiencyVSAvoidtoner charge stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The continuous toner layer on the rotating sleeve is segmented into discrete portions within each recess. This segmentation allows efficient toner pickup during rotation while preventing congestion by limiting the amount of toner each recess can hold, maintaining charge stability through controlled distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rotating sleeve creates periodic action as each recess passes through the development zone, picking up and delivering toner in regular intervals. This periodic conveyance ensures consistent toner supply to the photosensitive drum while preventing congestion through the rhythmic emptying of each recess at designated positions.

Inventive Principle:

Principle #19Periodic action

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 ensures stable toner charging and prevents toner congestion, resulting in improved image quality and extended durability by maintaining consistent toner supply and preventing issues like fogging or scattering.

Implementation Method 1

The fixed magnet includes a plurality of poles. The sleeve rotates around the fixed magnet, and carries the developer on a surface of the sleeve

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The layer-thickness limiting member limits thickness of the developer that is carried by the sleeve

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS10222726B2Developing device and image forming apparatus including the same

Publication Date: 2019.03.05 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

A developing device includes a development roller, a layer-thickness limiting member, and a first screw. The development roller includes a fixed magnet and a sleeve. The first screw supplies developer to the development roller while conveying the developer in a first conveyance direction. The sleeve includes a plurality of recesses. Each of the recesses has an elongated shape, and a downstream end and an upstream end in the first conveyance direction. The downstream end is located farther downstream in a rotational direction of the sleeve than the upstream end. When the developer in each of the recesses passes the layer-thickness limiting member, the developer moves upstream in the first conveyance direction.