Charge Elimination Member for Electrophotographic Fixing Device

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Solution Overview

Problem

In electrophotographic image forming apparatuses, the accumulation of electric charges on the fixing member and recording medium leads to inefficient charge elimination, affecting image quality and device performance.

Innovation Solution

A fixing device with a charge elimination member placed downstream of the fixing-and-nipping part, electrically connected to a contact sheet metal maintained at a specified potential, ensures effective charge elimination from both the recording medium and the fixing member through a contact member and retaining mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a charge elimination member is provided on the downstream side of the fixing-and-nipping part to perform charge elimination from the recording medium, then charge elimination efficiency is improved, but the device complexity and space requirements increase due to the need for additional contact sheet metal and electrical connection components

Engineering Contradiction:

Improvecharge elimination efficiencyVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the charge elimination function with the existing fixing housing structure. The contact sheet metal is integrated into the fixing housing, and the charge elimination member is positioned to utilize the same space where the recording medium passes through. This merging of functions reduces the need for separate charge elimination components and simplifies the overall device structure while maintaining effective charge elimination from both the recording medium and fixing member.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If additional contact sheet metal and electrical connection components are added to maintain charge elimination, then charge elimination reliability is improved, but the manufacturing complexity and assembly difficulty increase

Engineering Contradiction:

Improvecharge elimination reliabilityVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The contact sheet metal serves multiple functions: it acts as an electrical connection path between the charge elimination member and ground, serves as a structural support element within the fixing housing, and provides a contact surface for the recording medium. This multi-functionality reduces the number of separate components needed, simplifying both manufacturing and assembly processes while ensuring reliable charge elimination.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the charge elimination member is positioned to contact the recording medium downstream of the fixing-and-nipping part, then charge elimination effectiveness is improved, but the available space for component placement is reduced

Engineering Contradiction:

Improvecharge elimination effectivenessVSAvoidavailable space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The charge elimination member is positioned in the longitudinal direction (downstream side) of the fixing-and-nipping part, utilizing the space along the recording medium conveyance path. This dimensional arrangement allows the charge elimination function to be integrated into the existing convection path without requiring additional lateral or vertical space, effectively using the available longitudinal space for dual purposes: fixing and charge elimination.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 maintains image quality by ensuring reliable charge elimination, preventing toner sticking and paper dust accumulation on conveyance rollers, and reduces the need for additional space or complexity in the device design.

Implementation Method 1

The charge elimination member serves for charge elimination from the recording medium by making contact with the recording medium that has passed through a fixing-and-nipping part

Methodology Applied

Scientific EffectCharge conduction: Conduction (electrical)

Implementation Method 2

The first contact member electrically connects the charge elimination member and the contact sheet metal to each other

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9915899B2Fixing device for fixing toner image and image forming apparatus including the same

Publication Date: 2018.03.13 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

The fixing device includes a charge elimination member, a retaining member, a contact sheet metal, and a first contact member. The charge elimination member performs charge elimination from a recording medium by making contact with the recording medium that has passed through a fixing-and-nipping part. The retaining member has the charge elimination member fixed thereto. The contact sheet metal is held at a specified potential. The first contact member electrically connects the charge elimination member and the contact sheet metal to each other. The retaining member has a hollow cylindrical-shaped positioning boss, and the fixing housing has an insertion hole into which the positioning boss is to be inserted. The first contact member is placed inside the positioning boss and has one end protruded from the positioning boss. The contact sheet metal is placed so as to face the positioning boss.