Fixing Device Heater Contact Amount Variation

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Solution Overview

Problem

Existing image forming apparatuses face issues with uneven temperature distribution in the fixing belt due to uneven heating, leading to variations in toner image gloss and potential fixing failures, especially when using a fixing belt with decreased thermal capacity for energy efficiency and high-speed printing.

Innovation Solution

The implementation of a fixing device with a heater that has varying contact amounts with a holder along its longitudinal direction, incorporating resistive heat generators connected in series or parallel, and notches on the heater holder to manage heat distribution, ensuring consistent temperature across the fixing belt.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a fixing belt with decreased thermal capacity is used to save energy and achieve high-speed printing, then energy efficiency and printing speed are improved, but temperature uniformity of the fixing belt deteriorates

Engineering Contradiction:

Improveprinting speedVSAvoidtemperature uniformity

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The heater holder is designed with varying contact amounts at different longitudinal positions to create local heat compensation. The contact amount is increased at positions where heat is lost to contact members, and decreased at other positions, achieving uniform temperature distribution across the fixing belt while maintaining high-speed printing capability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heater holder's contact amount parameter is intentionally varied along the longitudinal direction of the heater. This parameter change compensates for non-uniform heat loss, ensuring that the fixing belt receives uniform heat distribution even when using a thin fixing belt with low thermal capacity for high-speed printing

Inventive Principle:

Principle #35Parameter changes

2Temperature

If a heater heats the fixing belt uniformly, then temperature uniformity is improved, but energy consumption increases due to heat loss to contact members

Engineering Contradiction:

Improvetemperature uniformityVSAvoidenergy consumption

Core Design Contradiction:

TemperatureVSUse of energy by stationary object

Solution Approach 1:

Instead of uniform heating, the heater applies localized heat compensation by varying contact amounts at different positions. This reduces overall energy consumption by avoiding unnecessary heating in areas where contact members do not cause significant heat loss, while still achieving uniform temperature distribution

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heat loss to contact members is converted into a beneficial effect by strategically positioning the heater holder to increase contact amounts at specific locations. This transforms the harmful heat loss into a mechanism for local heat compensation, reducing total energy consumption while maintaining temperature uniformity

Inventive Principle:

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

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 maintains a uniform temperature along the fixing belt, preventing toner image gloss variations and fixing failures, while allowing for energy-efficient high-speed printing.

Implementation Method 1

The heater contacts the holder with a first contact amount in a first span in a longitudinal direction of the heater, where the contact member contacts the fixing belt. The heater contacts the holder with a second contact amount, that is greater than the first contact amount, in a second span in the longitudinal direction of the heater, where the contact member does not contact the fixing belt.

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The heater includes a first heat generator and a second heat generator arranged with the first heat generator in a longitudinal direction of the heater with a gap between the first heat generator and the second heat generator.

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10747154B2Fixing device and image forming apparatus

Publication Date: 2020.08.18 RICOH CO LTD

AI summary

A fixing device includes a fixing belt that is endless and rotates in a rotation direction. A pressure rotator presses against the fixing belt to form a nip between the fixing belt and the pressure rotator. A heater is disposed opposite an inner circumferential surface of the fixing belt and heats the fixing belt. A contact member contacts the fixing belt partially in a longitudinal direction of the fixing belt. A holder holds the heater. The heater contacts the holder with a first contact amount in a first span in a longitudinal direction of the heater, where the contact member contacts the fixing belt. The heater contacts the holder with a second contact amount, that is greater than the first contact amount, in a second span in the longitudinal direction of the heater, where the contact member does not contact the fixing belt.