Planar Heater Segmentation for Fixing Belt Temperature Uniformity

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Solution Overview

Problem

Existing heating devices for fixing toner images on recording media face challenges in maintaining uniform temperature distribution across the fixing belt, leading to temperature unevenness and inefficiencies in image fixation.

Innovation Solution

The proposed heating device incorporates a planar heater with resistive heat generators arranged in a specific configuration, including separation regions, and a holder with clearance structures to reduce heat transfer and maintain efficient heating, ensuring uniform temperature distribution across the fixing belt.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the planar heater has continuous contact with the holder across all regions, then structural support is maximized, but temperature uniformity deteriorates due to heat loss through the holder

Engineering Contradiction:

Improvetemperature uniformityVSAvoidheat loss

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The holder is segmented into multiple regions with different contact characteristics: first contact regions where the planar heater contacts the holder, and second contact regions (clearance structures) where the planar heater does not contact the holder. This segmentation allows selective heat management - maintaining structural support where needed while reducing heat loss in specific areas to improve temperature uniformity across the fixing belt.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the holder are given different thermal properties through the clearance structures. The first contact regions provide thermal conduction for structural stability, while the second contact regions provide thermal insulation by creating clearance spaces. This local differentiation of contact quality enables the system to maintain both structural integrity and temperature uniformity.

Inventive Principle:

Principle #3Local quality

2Temperature

If heat generators are arranged continuously without separation, then heating coverage is maximized, but temperature control precision deteriorates due to hot spots and uneven distribution

Engineering Contradiction:

Improvetemperature distribution uniformityVSAvoidtemperature control precision

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The planar heater is segmented into multiple heat generator units arranged in series along the circumferential direction. Separation regions are introduced between these heat generator units, creating distinct heating zones. This segmentation prevents excessive heat concentration in any single area, allowing for more uniform temperature distribution and better temperature control precision across the fixing belt.

Inventive Principle:

Principle #1Segmentation

3Temperature

If the holder contacts the planar heater across the entire surface, then mechanical support is maximized, but heat transfer efficiency to the fixing belt deteriorates due to heat diversion to the holder

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidmechanical support

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The contact interface between the planar heater and holder is segmented into first contact regions (for mechanical support) and second contact regions with clearance structures (for heat transfer optimization). This segmentation ensures that mechanical support is provided only where necessary, while minimizing heat diversion to the holder and maximizing heat transfer efficiency to the fixing belt in the active heating regions.

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

This configuration enhances temperature uniformity along the fixing belt, reduces heat loss, and improves the fixation process by minimizing temperature drops and creases on the sheet, leading to better image quality and reduced operational issues.

Implementation Method 1

a planar heater (22) heating the fixing belt (20) from inside the loop. One type of such a heater includes a plurality of resistive heat generators arranged and electrically coupled in parallel to each other, as main heat generation portions

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The holder includes at least one clearance structure configured to cause a contact area between the planar heater and a portion of the holder corresponding to the at least one separation region to be smaller than a contact area between the planar heater and a portion of the holder not corresponding to the at least one separation region

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11687020B2Heating device, fixing device, and image forming apparatus

Publication Date: 2023.06.27 RICOH CO LTD

AI summary

A heating device includes a heating rotator, a pressure rotator, a planar heater, and a holder. The pressure rotator is configured to press against the fixing rotator to form a nip through which the recording medium is conveyed. The planar heater includes a plurality of heat generators arranged side by side and at least one separation region between the plurality of heat generators. The holder holds the planar heater and contacts the planar heater in a pressure direction in which the pressure rotator presses the heating rotator. The holder includes at least one clearance structure configured to cause a contact area between the planar heater and a portion of the holder corresponding to the at least one separation region to be smaller than a contact area between the planar heater and a portion of the holder not corresponding to the at least one separation region.