Charging Roller Shaft Joint Geometry for Load Distribution

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In electrophotographic image forming apparatuses, the crossing angle between the charging roller and the photosensitive member can exceed the engagement angle of the hollow metal shaft's depression-protrusion joint, leading to uneven load distribution and deterioration of cylindricity and total deflection of the charging roller.

Innovation Solution

A roller design with a cylindrical shaft featuring a depression-protrusion joint where the facing surfaces are inclined at a predetermined engagement angle, ensuring the crossing angle between the circumferential surfaces of the roller and the rotating member is smaller than the engagement angle, thereby distributing the load uniformly and preventing deflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the crossing angle between the charging roller and the photosensitive member is made larger to improve contact pressure distribution, then the engagement angle of the depression-protrusion joint becomes insufficient, causing load concentration on one end side of the non-parallel portion

Engineering Contradiction:

Improvecontact pressure distributionVSAvoidcylindricity and total deflection

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The invention changes the geometric parameters of the joint by introducing a depression-protrusion structure with a specific engagement angle (3° to 15°) and controlling the crossing angle (0° to 5°), ensuring the engagement angle is larger than the crossing angle to distribute load uniformly across the joint

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates an asymmetric depression-protrusion joint structure where the facing surfaces are inclined at a predetermined engagement angle, allowing the roller to maintain stable contact while distributing loads uniformly across the joint rather than concentrating them at one end

Inventive Principle:

Principle #4Asymmetry

2Manufacturing precision

If the engagement angle of the depression-protrusion joint is increased to improve load distribution, then the crossing angle between the rollers must be controlled, but this limits the design flexibility

Engineering Contradiction:

Improveload distribution uniformityVSAvoiddesign flexibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention provides specific parameter ranges (engagement angle: 3° to 15°, crossing angle: 0° to 5°) that balance load distribution with design flexibility, allowing engineers to adjust within these ranges based on specific application requirements

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9996020B2Roller, rotating member unit, cartridge, and image forming apparatus

Publication Date: 2018.06.12 CANON KK

AI summary

A cylindrical shaft of a roller has facing surfaces which form a depression-protrusion-shaped portion of a joint of the cylindrical shaft and which face or make contact with each other and moreover which extend in a direction non-parallel to an axial direction of the cylindrical shaft, and the facing surfaces are inclined at a predetermined engagement angle with respect to a circumferential direction. A generating line of a circumferential surface of a coating layer that coats an outer circumference of the cylindrical shaft and a generating line of a circumferential surface of a photosensitive drum cross each other at a crossing angle smaller than the engagement angle.