Drum Unit Bearing Positioning for Cleaner Precision

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Solution Overview

Problem

Existing drum units in electrophotographic image forming apparatuses face challenges in achieving precise positioning of cleaning members relative to photosensitive drums, which affects the effectiveness of surface cleaning operations.

Innovation Solution

The drum unit design incorporates a first and second side plate, a photosensitive drum, a cleaner, and a bearing system, where the cleaner is supported by a frame and the bearing extends through openings in both side plates to securely position the cleaner relative to the drum, enhancing precision and stability during cleaning operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cleaning member is disposed with high precision relative to the photosensitive drum, then cleaning effectiveness is improved, but device complexity increases

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidpositioning structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical positioning mechanisms with a bearing system that uses rotational freedom to achieve precise positioning. The bearing allows the photosensitive drum to rotate while maintaining a fixed axial position and precise radial alignment with the cleaner, eliminating the need for complex mechanical constraints.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The bearing serves multiple functions simultaneously: it supports the photosensitive drum axially, enables rotational motion, and maintains precise positioning relative to the cleaner. This multi-functionality reduces the need for separate positioning mechanisms, thereby reducing overall device complexity while maintaining cleaning effectiveness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If the photosensitive drum position is fixed in the first direction, then positioning precision of cleaner is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecleaner positioning precisionVSAvoiddrum position fixation precision

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The bearing acts as an intermediary component between the photosensitive drum and the cleaner. It provides a standardized interface that maintains precise positioning while accommodating manufacturing tolerances. The bearing's internal geometry ensures consistent radial alignment and axial positioning, reducing the precision requirements for the overall assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9239564B2Drum unit capable of improving positioning precision of cleaner with respect to photosensitive drum

Publication Date: 2016.01.19 BROTHER KOGYO KK

AI summary

A drum unit includes: a first side plate; a second side plate; a photosensitive drum; a cleaner; a first frame; and a bearing. The first side plate has a first opening. The second side plate is spaced apart from the first side plate in a first direction. The photosensitive drum has an axis extending along the first direction and a first end portion in the first direction. The photosensitive drum has a circumferential surface. The cleaner is configured to clean the circumferential surface of the photosensitive drum. The first frame includes: a support portion configured to support the cleaner; and a wall portion having a second opening. The bearing is configured to support the first end portion of the photosensitive drum. The bearing extends through both the first opening and the second opening.