Developing Device Filter Holder for Toner Leak Prevention

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Solution Overview

Problem

Conventional developing devices in image forming apparatuses face the issue of air leakage from the lateral sides of the filter, leading to toner scattering outside the device, as the filter's collection function is not fully exerted.

Innovation Solution

A developing device with a filter holder that ensures the filter is disposed in an opening portion to prevent air leakage, using a two-layer structure with varying weight densities and compression to enhance adhesion, reducing toner scattering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a filter is disposed in an opening portion to collect toner, then toner collection function is improved, but air leaks from lateral sides of the filter causing toner scattering

Engineering Contradiction:
Improvetoner collection functionVSAvoidair leakage and toner scattering
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies this principle by using an elastic member (elastomeric material) that forms a flexible seal between the filter assembly and the developing device housing. The elastic member deforms to conform to the opening portion, creating a tight seal that prevents air and toner leakage from lateral sides while maintaining the filter's toner collection function

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent applies this principle by introducing an elastic member as an intermediary element between the filter assembly and the housing. This intermediary component mediates the connection, providing both mechanical support and sealing functionality, thereby preventing air leakage without compromising the filter's ability to collect toner

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the filter is compressed to enhance adhesion, then sealing performance is improved, but filter structure may be damaged

Engineering Contradiction:
Improvesealing performanceVSAvoidfilter structure integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies this principle by carefully controlling the compression parameter - the elastic member is designed to apply sufficient compressive force to achieve good sealing contact, while the compression amount is limited to within 1/4 of the elastic member's thickness, preventing excessive compression that would damage the filter structure

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies this principle by making the elastic member's physical properties non-uniform - specifically, the thickness varies in the width direction, being thicker at both ends and thinner in the intermediate portion. This local quality variation ensures uniform contact pressure distribution and prevents filter damage while maintaining sealing performance

Inventive Principle:
Principle #3Local quality

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

The filter effectively collects toner while preventing air leakage, maintaining internal pressure and enhancing toner collection performance, thus reducing toner scattering and clogging.

Implementation Method 1

a filter (26t) is disposed in the opening portion (26k1)

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 2

the filter (26t) is compressed in a width direction by the elastic member (26k13)

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 3

an elastic member (26k13) having a first end and a second end opposite to each other in the width direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4226216B1Developing device, process cartridge, and image forming apparatus
Publication Date: 2025.07.02 RICOH CO LTD
  • EP4226216B1 patent drawingFigure 1
  • EP4226216B1 patent drawingFigure 2A~2B
  • EP4226216B1 patent drawingFigure 3~4B

AI summary

A filter holding device includes an opening portion and a filter. The opening portion communicates an inside of the filter holding device with an outside of the filter holding device, and has a rim that extends in a communication direction from the inside of the filter holding device toward the outside of the filter holding device. The filter is disposed in the opening portion, and has a first side and a second side. The first side faces the inside of the filter holding device. The second side faces the outside of the filter holding device. The filter has a larger weight density per unit volume at the second side facing the outside of the filter holding device than at the first side facing the inside of the filter holding device in a state in which the filter is disposed in the opening portion.