Fuser Separator Insulation Using a High-Resistance Resin Collar

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Solution Overview

Problem

The existing fixing devices face issues with insulation breakdown between the separator and the housing, leading to current flow that affects heat generation and damages peripheral components.

Innovation Solution

A fixing device design that includes a resistor assembly between the separator and the housing, ensuring insulation through a conductive separator and biasing member, using a collar with high volume resistance to limit current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conductive separator is used to separate the sheet from the fixing belt, then separation performance is improved, but current flows from the heater to the housing via the separator and biasing member, affecting heat generation and damaging peripheral components

Engineering Contradiction:
Improveseparation performanceVSAvoidcurrent flow
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A resin collar with high volume resistance is introduced as an intermediary component between the conductive separator and the housing. This collar acts as an electrical insulator that blocks the harmful current flow path while allowing the separator to maintain its mechanical function of separating sheets from the fixing belt. The collar is positioned at the contact point where the separator assembly interfaces with the housing, effectively interrupting the electrical conduction path without interfering with the mechanical separation operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the insulation layer on the heater is broken, then current flows through the fixing belt and separator to the housing, but this affects the amount of heat generated by the heater and adversely affects peripheral members

Engineering Contradiction:
Improveinsulation integrityVSAvoidheat variation and component damage
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The resin collar is installed in advance as a protective measure to prevent potential current flow through the separator assembly. By positioning the high-resistance collar between the conductive separator and the housing before operation, the system is pre-protected against insulation breakdown scenarios. This preventive approach ensures that even if the heater's insulation layer fails, the current path is blocked at the collar, preventing heat generation variations and protecting peripheral components from electrical damage.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If a metal separator is used as disclosed in PTL1, then separation function is achieved, but electrical conductivity creates a current path from heater to housing

Engineering Contradiction:
Improveseparation functionVSAvoidelectrical insulation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The separator assembly is segmented into distinct functional components: a conductive separator portion that performs the mechanical separation function, and a resin collar portion that provides electrical insulation. This segmentation allows each component to fulfill its specific role - the metal separator contacts the fixing belt to prevent sheet adhesion, while the resin collar interrupts the electrical path to the housing. The assembly combines these materials strategically to achieve both separation efficacy and electrical safety.

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

Secures insulation between the separator and housing, preventing heat variation and component damage, while reducing toner adhesion and electrical charge accumulation.

Implementation Method 1

Applying an alternating current (AC) voltage to the resistive heat generator generates heat

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The collar is made of a resin and has a high volume resistance so as to limit a current flowing from the heater to the housing

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentEP4469863B1Fixing device and image forming apparatus incorporating same
Publication Date: 2026.02.04 RICOH CO LTD
  • EP4469863B1 patent drawingFigure 1
  • EP4469863B1 patent drawingFigure 2~3
  • EP4469863B1 patent drawingFigure 4

AI summary

A fixing device includes a rotator (20, 120), an opposed rotator (21, 93), a heater (22), a housing (40), a resistor (42), a separator (41), and a biasing member (44). The opposed rotator is opposite the rotator. The heater includes a resistive heat generator (31). The heater is in direct contact with the inner circumferential surface of the rotator or in contact with the inner circumferential surface of the rotator via a conductive member (28, 36) to heat the rotator. The housing is conductive and grounded. The resistor is in the housing. The separator is conductive and is in contact with the rotator. The separator is assembled into the housing via the resistor. The biasing member biases the separator against the rotator. The biasing member is assembled into the housing via the resistor.