Fixing Device Pivot Restrictor for Conductive Member Alignment

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Solution Overview

Problem

Existing image forming apparatuses suffer from banding images due to the alternating current voltage affecting the transfer electric field at the transfer nip, especially in high-humidity environments or with thin sheets.

Innovation Solution

The implementation of a fixing device with a conductive member that contacts the inner face of the fixing belt and pivots, featuring a holding portion, a contact portion, and a pivot restrictor to prevent pivoting and ensure proper contact, thereby grounding the alternating current voltage and preventing banding images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the conductive member is allowed to pivot freely, then the ease of operation is improved, but the manufacturing precision deteriorates due to improper contact with the fixing belt

Engineering Contradiction:

Improveease of installationVSAvoidcontact position accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The pivot restrictor is pre-installed on the heater holder to define the correct contact position before the conductive member is installed. This preliminary positioning structure guides the conductive member into proper alignment, ensuring accurate contact with the fixing belt while maintaining ease of installation.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the conductive member contacts the fixing belt, then the harmful factors are reduced by grounding AC voltage, but the device complexity increases due to additional components

Engineering Contradiction:

Improvebanding imageVSAvoidstructure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The conductive member serves multiple functions: it provides electrical grounding to eliminate banding images, acts as a positioning element for the heater assembly, and functions as a structural support component. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pivot restrictor acts as an intermediary element between the heater holder and the conductive member, controlling the contact position and preventing excessive pivoting. This intermediary structure ensures proper grounding function while maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the conductive member pivots excessively, then the adaptability is improved for accommodating variations, but the reliability deteriorates due to loss of proper contact

Engineering Contradiction:

Improveposition toleranceVSAvoidcontact stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The pivot restrictor allows for a controlled range of pivoting motion, providing dynamic adjustment capability within defined limits. This enables the conductive member to accommodate minor position variations and assembly tolerances while preventing excessive pivoting that would compromise contact stability and grounding reliability.

Inventive Principle:

Principle #15Dynamics

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

The solution effectively prevents the formation of banding images by ensuring that the alternating current voltage is properly grounded, improving the uniformity of the image transferred onto the sheet.

Implementation Method 1

A pivot restrictor contacts the outboard portion of the conductive member. The pivot restrictor restricts pivoting of the conductive member about the one end portion of the conductive member.

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 2

The conductive member includes one end portion in the rotation direction of the belt, a contact portion that contacts the belt, and an outboard portion that is disposed outboard from the contact portion in the rotation direction of the belt

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

The heater includes a base, a resistive heat generator mounted on the base, and an insulating layer. As the resistive heat generator is applied with an alternating current (AC) voltage, the resistive heat generator generates heat, thus heating an inner circumferential face of the fixing belt through the insulating layer and the like.

Methodology Applied

Scientific EffectResistive heating: Joule Heating

Data Source

PatentUS12339604B2Fixing device and image forming apparatus including a pivot restrictor to restrict pivoting of a conductive member

Publication Date: 2025.06.24 RICOH CO LTD

AI summary

A fixing device includes a belt that rotates in a rotation direction and a heater that heats the belt. A conductive member contacts an inner face of the belt and pivots. The conductive member includes one end portion in the rotation direction of the belt, a contact portion that contacts the belt, and an outboard portion that is disposed outboard from the contact portion in the rotation direction of the belt. A holding portion holds the one end portion of the conductive member. A pivot restrictor contacts the outboard portion of the conductive member. The pivot restrictor restricts pivoting of the conductive member about the one end portion of the conductive member.