Optical Scanner Housing Cover Light-Blocking Wall

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Solution Overview

Problem

In image forming apparatuses using electrophotographic methods, stray light from the optical scanning apparatus can cause abnormally formed electrostatic latent images on the photosensitive drum due to reflections from the fθ lens, and existing light-blocking solutions interfere with automatic assembly processes.

Innovation Solution

The image forming apparatus incorporates a light-blocking member within the housing cover of the optical scanning apparatus, specifically designed to block stray light emitted from the fθ lens during assembly, using a housing cover with integrated light-blocking wall portions that do not interfere with the automatic assembly of optical components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a light-blocking wall is provided in the housing to block stray light, then stray light prevention is improved, but automatic assembly is hindered due to interference with the positioning jig

Engineering Contradiction:

Improvestray lightVSAvoidautomatic assembly

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The light-blocking function is segmented from the housing and integrated into the housing cover instead. The housing cover includes light-blocking wall portions that are separate from the main housing structure, allowing the positioning jig to access the housing without obstruction while still providing effective stray light blocking when the cover is attached.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The light-blocking structure is moved from the horizontal plane (inside the housing) to the vertical plane (on the housing cover that covers the housing). This dimensional shift allows the light-blocking wall portions to extend from the inner surface of the housing cover toward the fθ lens, effectively blocking stray light while not interfering with the positioning jig's access to the housing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a light-blocking sheet is attached to the housing to block stray light, then stray light prevention is improved, but assembly complexity increases due to additional attachment steps

Engineering Contradiction:

Improvestray lightVSAvoidassembly process

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The light-blocking wall portions are merged with the housing cover as an integral structure rather than being separate attachment components. This integration eliminates the need for additional attachment steps and reduces assembly complexity, while still providing effective stray light blocking functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The housing cover serves dual functions: it covers the housing (protective function) and provides light-blocking wall portions to prevent stray light (optical function). This self-service approach combines multiple functions into a single component, reducing the overall number of parts and simplifying the assembly process.

Inventive Principle:

Principle #25Self-service

3Productivity

If the fθ lens is automatically assembled in the housing, then productivity is improved, but light-blocking wall placement becomes difficult due to jig interference

Engineering Contradiction:

Improveautomatic assembly speedVSAvoidlight-blocking wall positioning

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The light-blocking function is segmented into the housing cover, which is attached separately from the housing. This allows the fθ lens to be automatically assembled in the housing without obstruction, maintaining high productivity, while the light-blocking wall portions are precisely positioned on the housing cover to ensure accurate stray light blocking.

Inventive Principle:

Principle #1Segmentation

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 solution effectively prevents stray light from reaching the photosensitive drum, ensuring accurate image formation without disrupting the automatic assembly of optical components, thereby maintaining image quality and facilitating seamless assembly processes.

Implementation Method 1

a light blocking member that blocks stray light of the laser beam emitted from the optical scanning apparatus or that blocks a laser beam having a possibility to be the stray light among the laser beams emitted from the optical scanning apparatus

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 2

The reflected light from the polygon mirror is incident on the end surface in the longitudinal direction of the fθ lens, the incident light is reflected on the end surface of the fθ lens and emitted therefrom, and the emitted light becomes the stray light

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS9335653B2Image forming apparatus

Publication Date: 2016.05.10 KK TOSHIBA

AI summary

According to an embodiment, an image forming apparatus includes an optical scanning apparatus. A housing cover of the optical scanning apparatus includes a light blocking member. The light blocking member blocks stray light of a laser beam emitted from the optical scanning apparatus or blocks a laser beam having a possibility to be the stray light among the laser beams emitted from the optical scanning apparatus.