Fuser Temperature Control via Dynamic Speed and Heat Management

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Solution Overview

Problem

Fuser assemblies in electrophotographic imaging devices face issues with 'hot offset' and 'cold offset' due to temperature inconsistencies, leading to poor toner fixation and subsequent sheet imaging problems.

Innovation Solution

A controller-regulated fuser assembly with a heated member and backup member, where the heater is preheated to a lower temperature before imaging and the motor speed is adjusted to match process speed only when media arrives, ensuring consistent fusing temperature and preventing overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the fuser assembly is designed with high thermal conductivity and low thermal mass to quickly reach fusing temperature, then the heating speed is improved, but the temperature becomes too high when media is not present at the fusing nip, causing hot offset

Engineering Contradiction:

Improveheating speedVSAvoidhot offset

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The motor speed is dynamically adjusted based on whether media is present at the fusing nip. When media is absent, the motor rotates at a first speed lower than the process speed to prevent overheating. When media arrives, the motor speed is increased to the process speed to ensure proper fusing. This dynamic speed adjustment resolves the contradiction between quick heating and preventing hot offset.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the fuser assembly operates at high speed continuously to maintain process speed, then productivity is improved, but the fusing temperature becomes too low at the trailing portion of the first sheet, causing cold offset

Engineering Contradiction:

Improveprocess speedVSAvoidcold offset

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The motor speed is adjusted in two stages: first rotating at a lower speed to prevent overheating during the approach phase, then increasing to the process speed when media arrives at the fusing nip. This dynamic adjustment ensures that the fuser assembly maintains optimal temperature for fusing while still achieving the required process speed for productivity.

Inventive Principle:

Principle #15Dynamics

3Temperature

If the heater temperature is increased before media arrives to ensure proper fusing temperature, then cold offset is prevented, but the heated and backup members become overly hot, causing hot offset

Engineering Contradiction:

Improvefusing temperatureVSAvoidhot offset

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The controller preheats the fuser assembly to a first temperature (lower than fusing temperature) before media arrives at the fusing nip. This preliminary heating action prepares the fuser for immediate fusing when media arrives, while the motor speed is simultaneously reduced to prevent excessive temperature buildup. This resolves the contradiction between ensuring proper fusing temperature and preventing hot offset.

Inventive Principle:

Principle #10Preliminary action

4Object-affected harmful factors

If the motor speed is reduced before media arrives to prevent overheating, then hot offset is prevented, but the fuser assembly takes longer to reach process speed, reducing productivity

Engineering Contradiction:

Improvehot offsetVSAvoidprocess speed

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The motor speed is dynamically adjusted based on the presence of media at the fusing nip. When media is absent, the motor rotates at a first speed lower than the process speed to prevent overheating. When media arrives, the motor speed is quickly increased to the process speed to ensure proper fusing. This dynamic adjustment resolves the contradiction between preventing hot offset and maintaining productivity.

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

This solution effectively prevents 'hot offset' and 'cold offset' by maintaining optimal fusing temperatures, improving toner fixation and reducing wear on components, thus enhancing the fuser assembly's performance and longevity.

Implementation Method 1

A heater heats the heated member... the controller operates the heater to heat the fuser assembly to a first temperature

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Toner fuses to media in the nip at a fusing temperature... the heated member and a backup member defining a fusing nip

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10606196B2Fuser temperature control in an imaging device

Publication Date: 2020.03.31 LEXMARK INTERNATIONAL INC

AI summary

A fuser assembly includes a heated member and a backup member defining a fusing nip. Toner fuses to media in the nip at a fusing temperature and process speed during an imaging operation. Upon receipt of a command to commence imaging, a controller operates a heater to heat the fuser assembly to a first temperature less than the fusing temperature and operates a motor to rotate the fuser assembly at a speed lower than the process speed to prevent overheating the heated and backup members. Before a first media reaches the fusing nip, a speed of the motor is increased to the process speed to properly advance the media through the nip at the process speed. Upon the first media arriving at the fusing nip, the controller increases the temperature of the heater to a second temperature greater than the first temperature to prevent cold offset.