Cleaning Unit Toner Reattachment Prevention via Inversion

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Solution Overview

Problem

Existing electrophotographic image forming apparatuses face issues with residual toner collection, as the cleaning brush and collection roller rotating in the same direction cause toner to be flicked back onto the photoconductor, leading to ineffective toner collection.

Innovation Solution

A cleaning unit comprising a brush rotary body, a toner collecting rotary body, a toner collecting blade, and a cleaning blade, where the brush rotary body and toner collecting rotary body rotate in the same direction as the image carrier, and the cleaning blade is positioned downstream to collect toner falling from the brush rotary body, with the tangential line passing through their contact area intersecting a non-contact surface of the cleaning blade, preventing toner from adhering to the photoconductor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the cleaning brush and collection roller rotate in the same direction, then the structure is simple and easy to operate, but the toner is flicked back onto the photoconductor causing ineffective toner collection

Engineering Contradiction:

Improvesimplicity of rotation mechanismVSAvoidtoner collection efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent applies inversion by making the collection roller rotate in the opposite direction to the cleaning brush. This reverses the conventional approach where both components rotate in the same direction, thereby preventing toner from being flicked back onto the photoconductor while maintaining effective toner collection

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If the cleaning brush contacts the collection roller to transfer toner, then toner collection is achieved, but toner is flicked off and reattached to the photoconductor

Engineering Contradiction:

Improvetoner collection capabilityVSAvoidtoner reattachment to photoconductor

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

By rotating the collection roller in the opposite direction to the cleaning brush, the patent inverts the relative motion between these components. This prevents the flicking action that causes toner to be thrown back onto the photoconductor, while still allowing effective toner transfer from the brush to the roller

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent converts the potentially harmful flicking action into a beneficial effect by utilizing the opposite rotation directions. The relative motion between the cleaning brush and collection roller, instead of causing toner scattering, now effectively transfers toner to the roller while preventing reattachment to the photoconductor

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If the cleaning blade is positioned to scrape toner from the photoconductor, then cleaning effectiveness is improved, but the cleaning blade wears out faster

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidcleaning blade life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces the collection roller as an intermediary component between the cleaning brush and the cleaning blade. This intermediary captures and holds the toner, reducing the burden on the cleaning blade and thereby extending its service life while maintaining cleaning effectiveness

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9201378B2Cleaning unit, process cartridge incorporating same, and image forming apparatus incorporating same

Publication Date: 2015.12.01 RICOH CO LTD

AI summary

A cleaning unit, which is included in a process cartridge or an image forming apparatus, includes a brush rotary body to remove toner, a toner collecting rotary body to collect the toner, a toner collecting blade to scrape the toner, and a cleaning blade to scrape the toner falling from the brush rotary body. The image carrier, the brush rotary body, and the toner collecting rotary body rotate in the same direction. The cleaning blade, the brush rotary body, and the toner collecting rotary body are located to cause a tangential line passing through a contact area of the brush rotary body and the toner collecting rotary body on an outer peripheral circle around a shaft of the brush rotary body to have an intersection point intersecting a non-contact surface of the cleaning blade disposed opposite to a contact portion of the cleaning blade with the image carrier.