Segmented Heat Device for Image Fixing Duty Control

Solution Overview

Problem

Existing heat devices for image forming apparatuses face issues with excessive temperature rise in non-sheet feeding areas during continuous printing of small-size recording materials, leading to thermal damage and fixing failures when switching to large-size materials, which necessitates reduced heat generation and controlled turn-on duty ratios for separate heaters.

Innovation Solution

A heat device with at least two separately electrified heat generation members, where the turn-on duty ratio is adjusted to decrease the maximum heat generation during continuous conveyance, using a temperature detecting unit to control the heat generation distribution based on detected and target temperature differences, ensuring the turn-on ratio of the first heating member is set as a condition to prevent electric power shortages and fixing failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the turn-on duty ratio of heat generation members is reduced to suppress excessive temperature rise in non-sheet feeding areas, then thermal damage is prevented, but the maximum amount of possible heat generation is decreased which may cause fixing failures

Engineering Contradiction:

Improvetemperature of non-sheet feeding areaVSAvoidfixing quality

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The heater is divided into multiple heat generation members (first heat generation member and second heat generation member) that can be independently controlled. This segmentation allows different turn-on duty ratios to be applied to different regions, enabling suppression of excessive temperature rise in non-sheet feeding areas while maintaining sufficient heat generation for reliable fixing in sheet feeding areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different heat generation members are assigned different turn-on duty ratios based on their functional requirements. The first heat generation member (corresponding to non-sheet feeding area) operates at a lower duty ratio to prevent thermal damage, while the second heat generation member (corresponding to sheet feeding area) operates at a higher duty ratio to ensure adequate heat generation for fixing, thus achieving local optimization of heat generation characteristics.

Inventive Principle:

Principle #3Local quality

2Use of energy by stationary object

If the turn-on duty ratio is switched to decrease maximum heat generation during continuous conveyance, then temperature control is improved, but electric power shortage may occur causing fixing failures

Engineering Contradiction:

Improveheat generation controlVSAvoidavailable electric power for fixing

Core Design Contradiction:

Use of energy by stationary objectVSPower

Solution Approach 1:

The heater is divided into multiple heat generation members (first heat generation member and second heat generation member) that can be independently controlled. This segmentation allows different turn-on duty ratios to be applied to different regions, enabling suppression of excessive temperature rise in non-sheet feeding areas while maintaining sufficient heat generation for reliable fixing in sheet feeding areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different heat generation members are assigned different turn-on duty ratios based on their functional requirements. The first heat generation member (corresponding to non-sheet feeding area) operates at a lower duty ratio to prevent thermal damage, while the second heat generation member (corresponding to sheet feeding area) operates at a higher duty ratio to ensure adequate heat generation for fixing, thus achieving local optimization of heat generation characteristics.

Inventive Principle:

Principle #3Local quality

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 effectively suppresses fixing failures due to electric power shortages by optimizing heat generation distribution, maintaining temperature control, and preventing thermal damage, thus enhancing the processing capability and reliability of the image forming apparatus.

Implementation Method 1

a heat source (9) including at least two heat generation members (8b1, 8b2) which are separately electrified

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a temperature detecting unit (12) for detecting a temperature of the heat source (9)

Methodology Applied

Scientific EffectTemperature detection:

Data Source

PatentUS7831163B2Heat device and image forming apparatus including the same

Publication Date: 2010.11.09 CANON KK

AI summary

Provided is a heat device which heats and fixes a developed image onto a recording material while nipping and conveying the recording material bearing the developed image by a nip portion, in which even when a turn-on duty ratio between at least two heat generation members provided to a heat source is switched in a direction in which a maximum amount of possible heat generation is decreased, in order to suppress generation of a fixing failure of the developed image formed on the recording material due to a shortage of electric power, in a case where the turn-on duty ratio of a second heat generation member to a first heat generation member is switched, at a predetermined timing, in a direction in which the maximum amount of possible heat generation is decreased, with respect to the at least two heat generation members provided to the heat source, it is set as a condition that a turn-on ratio of the first heating member at the timing is smaller than a predetermined value.