Asymmetric Hinge Mechanism for Door Warping Suppression

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Solution Overview

Problem

In electrophotographic image forming apparatuses, such as laser printers, the door member warps due to the arrangement of lock and hinge mechanisms being deviated from each other, causing rattling and dimensional issues, which are exacerbated by the need to absorb dimensional variations between the door and main body members.

Innovation Solution

The implementation of hinge mechanisms with a first hinge hole smaller than the second hinge hole, where the hinge shaft is pressed against the inner surfaces by a spring unit, allowing for effective absorption of dimensional variations while restricting movement and preventing warping, and positioning the lock mechanism to reduce bending moments on the door member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the hinge holes are made larger than the hinge shaft to absorb dimensional variation, then the door member can be reliably locked and the hinge shaft can easily slide, but the door member rattles due to rattling of the hinge mechanisms

Engineering Contradiction:

Improvelocking reliabilityVSAvoidrattling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a spring mechanism that changes the dimensional parameters of the hinge system dynamically. The spring applies elastic force to press the hinge shaft against the inner peripheral surface of the hinge hole, eliminating gaps and rattling while maintaining the larger hole size for dimensional variation absorption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The spring mechanism provides beforehand cushioning by pre-compressing the hinge shaft against the hinge hole surface. This elastic cushioning force compensates for dimensional variations and prevents rattling before it occurs during door operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If springs are added to press the hinge shaft against the inner peripheral surfaces of the hinge holes to reduce rattling, then rattling is reduced, but the door member warps due to bending moment from deviated lock and hinge mechanisms

Engineering Contradiction:

ImproverattlingVSAvoidwarping

Core Design Contradiction:

Object-affected harmful factorsVSShape

Solution Approach 1:

The patent modifies the hinge hole dimensions (making them asymmetric with different diameters) to change the mechanical parameters of the system. This allows the spring force to be applied optimally while restricting door member displacement to prevent warping.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by making the hinge holes asymmetric (different diameters at different positions). This local variation in hole size allows differential restriction of door movement, preventing warping while maintaining rattling reduction.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the lock mechanism and hinge mechanism are arranged deviated from each other to accommodate layout requirements, then other equipment can be laid out properly, but a bending moment is applied to the door member causing warping

Engineering Contradiction:

Improvelayout flexibilityVSAvoidwarping

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The patent changes the dimensional parameters of the hinge holes (making them asymmetric with different diameters) to compensate for the bending moment caused by the deviated arrangement of lock and hinge mechanisms. This allows maintained layout flexibility while preventing warping.

Inventive Principle:

Principle #35Parameter changes

4Shape

If the first hinge hole is made smaller than the second hinge hole to restrict door member displacement and suppress warping, then warping is suppressed, but the ability to absorb dimensional variation is reduced

Engineering Contradiction:

ImprovewarpingVSAvoiddimensional variation absorption

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent applies local quality by creating asymmetric hinge holes with different diameters at different positions. The larger second hinge hole absorbs dimensional variations, while the smaller first hinge hole restricts door displacement and prevents warping, achieving both functions through localized dimensional differences.

Inventive Principle:

Principle #3Local quality

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 suppresses warping of the door member while maintaining the ability to absorb dimensional variations, reducing manufacturing costs and weight, and improving the rigidity and usability of the door member.

Implementation Method 1

a spring unit which presses the hinge shaft against inner peripheral surfaces of the first and second hinge holes

Methodology Applied

Scientific EffectElastic force: Elasticity

Data Source

PatentUS7684731B2Image forming apparatus with hinge holes and spring

Publication Date: 2010.03.23 BROTHER KOGYO KK

AI summary

An image forming apparatus is described as including a door member for opening and closing an opening provided in a main body member; a hinge mechanism; and a lock mechanism. The hinge mechanism may include a first hinge hole and a second hinge hole which are provided in at least one of the door member and the main body member, and are arranged substantially coaxially while being spaced from each other, a hinge shaft inserted across the first hinge hole and the second hinge hole, and a spring unit which presses the hinge shaft against inner peripheral surfaces of the first and second hinge holes. The first hinge hole may be smaller in size than the second hinge hole.