Fixing Device Shield and Belt Holder for Endless Rotary Body

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses face challenges in reducing thermal and mechanical damage to the endless belt and ensuring efficient discharge of recording media, leading to overheating and mechanical deformation of the belt ends, as well as potential jamming issues.

Innovation Solution

A fixing device with a hollow, endless rotary body and a pressing body forming a fixing nip, where a shield is interposed between the rotary body and heaters to prevent overheating, and a belt holder supports the belt ends, with a separator ensuring smooth discharge, allowing for efficient heating and pressure application while minimizing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the heater heats the endless belt directly to reduce first print time and power consumption, then the heating efficiency is improved, but the lateral ends of the endless belt overheat and suffer thermal damage

Engineering Contradiction:

Improvefirst print timeVSAvoidthermal damage to endless belt

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a shield with a through-hole that selectively blocks heat radiation to different regions of the endless belt. The shield allows heat to reach the central portion of the belt (where recording medium passes) while blocking excessive heat from reaching the lateral ends (where recording medium does not pass). This creates local differentiation in heat distribution, solving the contradiction between efficient heating and preventing thermal damage.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the separator is disposed opposite the outer circumferential surface of the endless belt to separate recording medium, then the discharge smoothness is improved, but the separator may strike the endless belt and cause mechanical damage

Engineering Contradiction:

Improvedischarge smoothnessVSAvoidmechanical damage to endless belt

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a belt holder as an intermediary component between the separator and the endless belt. The belt holder supports the lateral ends of the endless belt, preventing them from contacting the separator. This intermediary structure maintains the separator's ability to discharge recording medium smoothly while protecting the endless belt from mechanical damage caused by separator strikes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If a thin endless belt is used to decrease thermal capacity, then the heating speed is improved, but the belt becomes more susceptible to thermal and mechanical damage

Engineering Contradiction:

Improveheating speedVSAvoidresistance to thermal and mechanical damage

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The shield with through-hole creates local quality differentiation in heat distribution, allowing the thin belt to be heated quickly in the central region while protecting the lateral ends from excessive heat. This localized heat management enables the use of thin belts for fast heating without compromising overall reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The belt holder acts as an intermediary support structure that protects the thin endless belt from mechanical damage. By supporting the lateral ends of the belt, the belt holder prevents the thin belt from suffering mechanical stress and damage, enabling the use of thin belts for rapid heating while maintaining reliability.

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

The solution reduces thermal and mechanical stress on the belt, prevents overheating, and ensures smooth discharge of recording media, enhancing the reliability and efficiency of the fixing process.

Implementation Method 1

At least one heater is disposed opposite an inner circumferential surface of the endless rotary body to heat the endless rotary body

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS9405250B2Fixing device capable of minimizing damage of endless rotary body and image forming apparatus incorporating same

Publication Date: 2016.08.02 RICOH CO LTD

AI summary

A fixing device includes at least one heater disposed opposite an inner circumferential surface of an endless rotary body to heat the endless rotary body and a shield interposed between the endless rotary body and the at least one heater to shield the endless rotary body from heat radiated from the at least one heater. A first size recording medium passes over a first passage region of the endless rotary body and a second size recording medium passes over a second passage region of the endless rotary body. The shield includes a notch disposed opposite a lateral end of the second passage region of the endless rotary body in an axial direction thereof. The lateral end of the second passage region overlaps a non-passage region of the endless rotary body in the axial direction thereof where the first size recording medium does not pass.