Light Guide Positioning in Image Forming Apparatus

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Solution Overview

Problem

Conventional electrophotographic image forming apparatuses face issues with contamination of the light source due to scattered toner particles and paper dust, which obstructs light emission and affects the precision of charge removal from the photosensitive drum, leading to poor image formation quality.

Innovation Solution

The apparatus includes a light source in the main casing and a photosensitive cartridge with a light guide, where the light guide is positioned between first and second walls, and a cover member surrounds the emitting part to seal gaps and improve positioning precision, ensuring accurate light incidence on the photosensitive drum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the light source is disposed in the main casing and the light guide is supported on the drum unit, then the light guide can move with the drum unit mounting and removal, but the positioning precision between the light guide and light source deteriorates

Engineering Contradiction:

Improvemounting and removal flexibilityVSAvoidpositioning precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

A positioning protrusion on the light guide fits into a positioning groove on the light source holder, serving as an intermediary mechanical feature that ensures precise alignment between the movable light guide and the stationary light source during drum unit installation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces loose mechanical support with a precision positioning mechanism using protrusion-groove engagement, ensuring that the light guide maintains accurate positional relationship with the light source even when the drum unit is repeatedly mounted and removed

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Illumination intensity

If the light source is exposed in the main casing, then light can be emitted to the light guide, but contamination from toner particles and paper dust increases

Engineering Contradiction:

Improvelight emissionVSAvoidcontamination

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

A transparent cover member is placed over the light source, forming a protective barrier that blocks toner particles and paper dust while allowing light to pass through to the light guide

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The transparent cover member acts as an intermediary between the light source and the contaminated environment, separating the light emission function from the contamination risk while maintaining optical transmission

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If toner particles and paper dust are scattered in the main casing during image forming, then the image forming process can proceed, but the light source becomes contaminated

Engineering Contradiction:

Improveimage forming operationVSAvoidlight source contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The transparent cover member provides continuous protection during image forming operations, allowing normal productivity while preventing contamination of the light source by scattered toner and paper dust

Inventive Principle:

Principle #30Flexible shells and thin films

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

This configuration effectively suppresses contamination of the light source, enhances the precision of light guide and light source positioning, and ensures reliable charge removal from the photosensitive drum, improving image formation quality.

Implementation Method 1

The light guide is configured to guide the light emitted from the light source to the surface of the photosensitive drum

Methodology Applied

Scientific EffectLight guidance: Optical Fibre

Implementation Method 2

light emitted from the light source enters the light guide through its right endface and is guided by the light guide to be irradiated onto the surface of the photosensitive drum. This irradiated light removes any residual charge from the surface of the photosensitive drum

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS9501033B2Image forming apparatus provided with light guide and light source

Publication Date: 2016.11.22 BROTHER KOGYO KK

AI summary

An image forming apparatus includes: a main casing; a light source; and a photosensitive cartridge. The light source is provided in the main casing and configured to emit a light. The photosensitive cartridge is mountable in the main casing in a mounting direction. The photosensitive cartridge includes: a photosensitive drum; a light guide; a first wall and a second wall. The photosensitive drum has a surface. The light guide is configured to guide the light emitted from the light source to the surface of the photosensitive drum to eliminate static on the surface of the photosensitive drum. The second wall is spaced apart from the first wall in a first direction that crosses the mounting direction. The light source is disposed between the first wall and the second wall when the photosensitive cartridge has been mounted in the main casing.