Development Device Partition for Uniform Image Density

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Solution Overview

Problem

In electrophotographic image forming apparatuses, the resupply of used developer with reduced toner concentration to the development roller leads to uneven image density, which existing configurations fail to prevent without increasing wear on the development roller or driving torque.

Innovation Solution

A development device with a partition between the developer carrier and the second transport member prevents the used developer from being resupplied to the developer carrier, using a magnetic field generator to form magnetic poles and a circulation path with separate transport chambers to manage developer flow, ensuring fresh toner is supplied while preventing used developer resupply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the developer transport member transports developer from the collection chamber back to the developer carrier, then developer circulation is maintained, but used developer with reduced toner concentration is resupplied causing uneven image density

Engineering Contradiction:

Improvedeveloper circulationVSAvoidimage density uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The developer transport chamber is divided into a first transport chamber for supplying fresh developer and a second transport chamber for collecting used developer. A partition wall separates these two chambers, preventing mixing and ensuring that only fresh developer is supplied to the developer carrier while used developer is properly collected and transported away.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If a partition is introduced to prevent used developer resupply, then image density uniformity is improved, but device complexity increases

Engineering Contradiction:

Improveimage density uniformityVSAvoidtransport chamber structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

3Quantity of substance

If the developer carrier is exposed to used developer, then developer concentration is reduced, but image quality becomes uneven

Engineering Contradiction:

Improvedeveloper concentrationVSAvoidimage density uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The used developer is extracted from the development system through the second transport chamber and transported away from the developer carrier. The partition wall ensures that the developer carrier only contacts fresh developer from the first transport chamber, preventing contamination with used developer and maintaining consistent developer concentration for uniform image density.

Inventive Principle:

Principle #2Taking out (Extraction)

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 reduces unevenness in image density by preventing the resupply of used developer, maintaining the integrity of the development roller and minimizing wear and torque, resulting in consistent image quality.

Implementation Method 1

Multiple magnets are fixed inside the developer carrier to form corresponding multiple magnetic poles around the developer carrier. The multiple magnetic poles include an attraction pole to attract the developer to the circumferential surface of the developer carrier

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The first developer transport member disposed in the first transport chamber supplies the developer to the developer carrier

Methodology Applied

Scientific EffectMechanical transport:

Implementation Method 3

The second developer transport member disposed in the second transport chamber transports the developer separated from the developer carrier in a longitudinal direction

Methodology Applied

Scientific EffectMechanical transport:

Implementation Method 4

a partition disposed between the developer carrier and the second transport member to prevent the developer in the second transport chamber from being supplied to the developer carrier

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS8326180B2Development device, process cartridge, and image forming apparatus

Publication Date: 2012.12.04 RICOH CO LTD

AI summary

A development device to develop a latent image with two-component developer includes a developer carrier disposed facing the image carrier, to carry the developer, a magnetic field generator disposed inside the developer carrier, to form multiple magnetic poles around the developer carrier, an interior wall dividing the interior of the development device into a first transport chamber and a second transport chamber parallel to the first transport chamber, a first transport member disposed in the first transport chamber, facing the developer carrier, to supply the developer to the developer carrier while transporting the developer longitudinally, a second transport member disposed in the second transport chamber, facing the developer carrier, to transport the developer separated from the developer carrier longitudinally, a partition disposed between the developer carrier and the second transport member to prevent resupply of the used developer in the second transport chamber from to the developer carrier.