Developing Device Grease Seal and Toner Purity

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Solution Overview

Problem

In image forming apparatuses, the mixture of oil content from grease with toner can lead to adverse effects on the image forming process due to toner leakage around the blade and seal interfaces in developing devices.

Innovation Solution

A developing device design featuring a casing with a first seal member and an oil filler to prevent oil content from entering the toner, using a second seal member positioned inwardly to prevent grease overflow and mixing with toner, ensuring a clean toner flow and improved image formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If grease is coated on the rear surface of the blade to fill the gap between the upper seal and the blade, then toner leakage is prevented, but oil content from the grease may overflow and mix with the toner, adversely affecting the image forming process

Engineering Contradiction:

Improvetoner leakage preventionVSAvoidoil content mixing with toner

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sealing structure is divided into multiple segments: the upper seal member for primary sealing, grease filling for gap sealing, and the additional seal member positioned inward to contain the grease. This segmentation prevents oil content from reaching the toner while maintaining effective sealing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The additional seal member acts as an intermediary barrier between the grease and the toner. It is positioned inward from the upper seal to prevent grease overflow while allowing the grease to perform its sealing function at the interface between the upper seal and the blade.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the upper seal is formed with sufficient width to contact both the rear surface of the blade and the rear surface of the blade holder, then sealing between these components is improved, but a gap is created due to the step between surfaces, allowing toner leakage

Engineering Contradiction:

Improvesealing between blade and blade holderVSAvoidtoner leakage from gap

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The grease acts as an intermediary filling material that occupies the gap created by the step between the blade and blade holder surfaces. The additional seal member provides a secondary barrier to prevent toner from accessing this gap region.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The grease is coated on the rear surface of the blade in advance before assembly, so that when the upper seal is installed, the grease is already positioned to fill the gap and prevent toner leakage.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7526224B2Developing device, process cartridge, and image forming apparatus

Publication Date: 2009.04.28 BROTHER KOGYO KK

AI summary

Gap among a leaf spring member of a layer-thickness regulating blade, a back-side member of a blade holder and a blade opposed portion of an upper seal is filled with grease. An internal seal is disposed laterally inward of the grease with a portion thereof sandwiched between the back surface of the leaf spring member and the blade opposed portion of the upper seal. This can prevent the grease from overflowing laterally inward from the gap among the back-side member, the leaf spring member and the upper seal, and can also prevent a toner from entering into a gap among the back-side member, the leaf spring member and the upper seal, thereby preventing the oil content of the grease from mixing into the toner.