Rotary Member Heating with Localized Temperature Control

Solution Overview

Problem

Conventional fixing apparatuses face challenges in maintaining optimal pre-heating operation time and preventing hot offset or poor fixing, especially when initial temperatures vary, as they often require setting uniform target temperatures for all regions of the rotary member, leading to inefficient heating and potential defects in image formation.

Innovation Solution

A fixing apparatus with two heaters having different heat generation distributions along the rotary member, where the central region and end regions are heated independently by a main-heater and sub-heater, respectively, and temperature detection portions control the heating to reach specific target temperatures based on the initial temperature, optimizing the pre-heating process to prevent hot offset and ensure adequate heat distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target temperature is set to a higher value to account for heat dispersion, then the pre-heating operation can ensure adequate heating, but excessive heat is supplied causing hot offset and extended pre-heating time

Engineering Contradiction:

Improveadequate heatingVSAvoidhot offset

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by setting different target temperatures for different regions of the rotary member. The central region uses a first target temperature while the end portions use a second target temperature that is lower than the first. This regional differentiation prevents excessive heat accumulation in the central region that causes hot offset, while still ensuring adequate heating at the end portions where heat dispersion is more significant.

Inventive Principle:

Principle #3Local quality

2Reliability

If the target temperature is set to a higher value to account for heat dispersion, then the pre-heating operation can ensure adequate heating, but the pre-heating operation time is extended excessively

Engineering Contradiction:

Improveadequate heatingVSAvoidpre-heating operation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by setting different target temperatures for different regions of the rotary member. The central region uses a first target temperature while the end portions use a second target temperature that is lower than the first. This regional differentiation prevents excessive heat accumulation in the central region that causes hot offset, while still ensuring adequate heating at the end portions where heat dispersion is more significant.

Inventive Principle:

Principle #3Local quality

3Device complexity

If the target temperature is set uniformly for all regions, then the control is simple, but the temperature distribution becomes non-uniform causing poor fixing at end portions or hot offset at central region

Engineering Contradiction:

Improvecontrol simplicityVSAvoidtemperature distribution uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by setting different target temperatures for different regions of the rotary member. The central region uses a first target temperature while the end portions use a second target temperature that is lower than the first. This regional differentiation prevents excessive heat accumulation in the central region that causes hot offset, while still ensuring adequate heating at the end portions where heat dispersion is more significant.

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

This solution reduces pre-heating operation time while maintaining uniform temperature distribution across the rotary member, preventing hot offset and ensuring proper fixing operations regardless of initial temperatures, thus enhancing image formation quality and efficiency.

Implementation Method 1

a first heater provided in the rotary member, a heat generation amount per unit length at a central region of the first heater in a longitudinal direction being greater than a heat generation amount at end regions of the first heater in a longitudinal direction; a second heater provided in the rotary member, a heat generation amount per unit length at end regions of the second heater in a longitudinal direction being greater than a heat generation amount of the second heater at a central region in a longitudinal direction

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS7865102B2Image fixing apparatus

Publication Date: 2011.01.04 CANON KK

AI summary

A fixing apparatus includes a control circuit which controls the electrifying to a first heater so that a temperature detected by a first temperature detection portion reaches a first target temperature and controls the electrifying to a second heater so that a temperature detected by a second temperature detection portion reaches a second target temperature, when warm-up is initiated, and, when the warm-up initiated, if an initial temperature of a rotary member is below a predetermined temperature, the control circuit sets the first target temperature to a temperature value greater than the first target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature and sets the second target temperature to a temperature value greater than the second target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature. In this way, hot offset and poor fixing can be prevented and a pre-heating operation time can be prevented from extending excessively.