Heating Device Pressure Roller Electrostatic Discharge via Resistor

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Solution Overview

Problem

Existing heating devices in fixing and drying applications face challenges in preventing electrostatic charging of the pressure roller, leading to fixation failures and wear of the fixing belt, while also risking electronic component charging and toner adhesion.

Innovation Solution

Incorporating a discharging brush grounded via a resistor to contact the conductive outer surface of the pressure roller, which removes static charge without requiring a conductive elastic layer, thus maintaining a sufficient fixing nip width and reducing wear, and using a resistor to limit current flow and prevent component charging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the pressure roller surface is made conductive to prevent electrostatic charging, then electrostatic offset is reduced, but the fixing belt wear increases and fixation failures occur

Engineering Contradiction:

Improveelectrostatic offsetVSAvoidfixation failure

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

A discharger is introduced as an intermediary component between the pressure roller and ground. The discharger contacts the conductive outer surface of the pressure roller and provides a controlled discharge path through a resistor to ground, allowing electrostatic charge to be safely dissipated without creating the harmful effects of direct grounding

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrical resistance parameter is controlled by selecting an appropriate resistor value in the discharger circuit. This resistance value is optimized to allow sufficient charge dissipation to prevent electrostatic offset while limiting the current to levels that prevent fixation failures and belt wear

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the pressure roller surface is made conductive to remove static charge, then electrostatic charging is reduced, but electronic components become charged and toner adheres to them

Engineering Contradiction:

Improveelectrostatic chargingVSAvoidtoner adhesion

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The discharger acts as an intermediary that controls the electrostatic discharge process. By introducing the resistor as part of this intermediary system, the discharge is controlled to occur through a defined path that prevents uncontrolled charge transfer to electronic components and toner

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conductive outer surface of the pressure roller, which initially causes harmful electrostatic effects, is converted into a beneficial feature by pairing it with the discharger system. The conductivity allows for controlled charge dissipation that prevents more severe electrostatic problems, turning the potential harm into a useful charge management mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If a conductive elastic layer is used in the pressure roller to ground the surface, then static charge is removed, but the fixing nip width becomes insufficient

Engineering Contradiction:

Improvestatic chargeVSAvoidfixing nip width

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The discharger serves as an external intermediary that provides the grounding function without requiring the conductive elastic layer within the pressure roller structure. This separation allows the pressure roller to maintain its mechanical properties and fixing nip width while the discharger handles the electrostatic charge dissipation

Inventive Principle:

Principle #24Intermediary (Mediator)

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 prevents electrostatic offset, reduces fixation failures, and minimizes the risk of electronic component charging and toner adhesion, while maintaining the fixing device's speed and reducing wear on the fixing belt.

Implementation Method 1

The discharger is in contact with the conductive outer surface of the pressure roller and grounded via the resistor and the heating device frame

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Implementation Method 2

grounded via the resistor and the heating device frame

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

A heating device according to an embodiment of the present disclosure includes a planar heater

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11906916B2Heating device, fixing device, drying device, laminator, and image forming apparatus

Publication Date: 2024.02.20 RICOH CO LTD

AI summary

A heating device includes a planar heater, a rotator, a pressure rotator, a heating device frame, a resistor, and a discharger. The pressure rotator has a conductive outer surface and presses the rotator. The heating device frame holds the pressure rotator. The discharger is in contact with the conductive outer surface of the pressure rotator and grounded via the resistor and the heating device frame.