Fixing Member Heating Patterns for Pressing Roller Temperature Control

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Solution Overview

Problem

Conventional image forming apparatuses without a heating unit on the pressing roller side face challenges in maintaining proper temperature control, leading to issues like uneven brightness and improper heat propagation, especially when handling different types of sheets.

Innovation Solution

An image forming apparatus with a controller that manages a heating unit for the fixing member, employing specific heating patterns based on sheet type and temperature measurements to optimize heating periods, even when there is no heating unit on the pressing roller side, ensuring accurate temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a heater is not provided on the pressing roller side to save energy, then energy consumption is reduced, but the temperature of the pressing roller cannot be properly controlled

Engineering Contradiction:

Improveenergy consumptionVSAvoidpressing roller temperature control

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The patent introduces a sheet as an intermediary heat transfer medium. The heater on the fixing member side heats the sheet, and the heated sheet then transfers heat to the pressing roller during the pressing operation. This indirect heat transfer mechanism allows the pressing roller to be heated without requiring a direct heating unit on it, thus saving energy while maintaining temperature control capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sheet serves a dual function: it is both the substrate for image formation and a heat transfer medium. By utilizing the sheet's inherent thermal properties and its necessary passage through the fixing assembly, the system enables self-heating of the pressing roller through the heated sheet, eliminating the need for separate heating mechanisms.

Inventive Principle:

Principle #25Self-service

2Temperature

If the heater is turned on during sheet interval to control pressing roller temperature, then temperature control is improved, but the fixing belt temperature fluctuates causing uneven brightness

Engineering Contradiction:

Improvepressing roller temperature controlVSAvoidbrightness uniformity

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The patent applies heating locally and selectively - the heater is positioned only on the fixing member side where it is needed for primary heat generation. The heat is then locally transferred to the pressing roller through the sheet at the specific location where sheets pass through the fixing assembly, avoiding unnecessary heating of the entire fixing belt and preventing brightness uniformity issues.

Inventive Principle:

Principle #3Local quality

3Temperature

If the pressing roller is heated continuously to maintain temperature, then temperature stability is improved, but energy consumption increases

Engineering Contradiction:

Improvepressing roller temperature stabilityVSAvoidenergy consumption

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

Instead of continuous heating, the system uses periodic heating through each passing sheet. Each sheet acts as a periodic heat transfer vehicle, delivering thermal energy to the pressing roller at regular intervals corresponding to the sheet feed rate. This periodic action maintains temperature stability while consuming energy only when sheets are present, rather than continuous energy input.

Inventive Principle:

Principle #19Periodic action

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 controls the temperature of the pressing roller, preventing defects such as uneven brightness and ensuring proper heat distribution across various sheet types, enhancing the quality of the image forming process.

Implementation Method 1

a heating unit which heats the fixing member

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the sheet is located at the fixing member in a first period... the fixing member heats a toner image formed on a sheet

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the temperature of the pressing roller is not able to properly controlled because degree of heat propagation to the pressing roller through a conveyed sheet is different depending on the type of a sheet

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9989902B2Image forming apparatus and computer readable medium storing program

Publication Date: 2018.06.05 KONICA MINOLTA INC

AI summary

An image forming apparatus includes a fixing member, a pressing member, a heating unit and a controller. The fixing member heats a toner image formed on a sheet. The pressing member presses the sheet onto the fixing member. The heating unit heats the fixing member. The controller controls the heating unit. The sheet is located at the fixing member in a first period and the sheet is not located at the fixing member and the fixing member is located between sheets in a second period. The controller controls the heating unit such that the heating unit heats the fixing member in a first heating pattern in which a heating period does not include the second period or in a second heating pattern in which a heating period includes the second period.