Fixing Apparatus Heater Power Control via Film Rotation

Solution Overview

Problem

Existing fixing apparatuses in electrophotographic image forming devices face thermal stress issues due to temperature differences between heated and unheated regions of the fixing film during warm-up, especially in low-temperature environments, which can deform the film and require additional components and sensors for rotation detection.

Innovation Solution

A fixing apparatus with a rotatable tubular film, a heater, a temperature sensing member, and a control unit that supplies first and second electric powers to the heater based on temperature increases sensed by the temperature sensing member, ensuring controlled heating and rotation synchronization to prevent thermal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If maximum power is supplied to the heater during warm-up to reduce warm-up time, then warm-up time is reduced, but thermal stress increases causing film deformation

Engineering Contradiction:

Improvewarm-up timeVSAvoidthermal stress

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of film rotation status before applying maximum heating power. The temperature sensing member detects temperature changes that indicate film rotation, and only after rotation is confirmed does the control unit supply maximum power to the heater. This preliminary action prevents thermal stress while enabling rapid warm-up.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the temperature sensing member to control heater power supply. The sensing member continuously monitors temperature changes, and the control unit adjusts heater power based on this feedback - supplying maximum power only when temperature increase indicates proper film rotation, otherwise limiting power to prevent thermal stress.

Inventive Principle:

Principle #23Feedback

2Speed

If maximum power is supplied to the heater while the film is stationary, then warm-up speed increases, but temperature difference between heated and unheated regions increases causing film deformation

Engineering Contradiction:

Improvewarm-up speedVSAvoidfilm uniformity

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The system performs preliminary detection of film rotation status before applying maximum heating power. The temperature sensing member detects temperature changes that indicate film rotation, and only after rotation is confirmed does the control unit supply maximum power to the heater. This preliminary action prevents thermal stress while enabling rapid warm-up.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the temperature sensing member to control heater power supply. The sensing member continuously monitors temperature changes, and the control unit adjusts heater power based on this feedback - supplying maximum power only when temperature increase indicates proper film rotation, otherwise limiting power to prevent thermal stress.

Inventive Principle:

Principle #23Feedback

3Reliability

If a rotation detection plate and sensor are added to detect film rotation, then heating can be synchronized with rotation, but device complexity and cost increase

Engineering Contradiction:

Improveheating synchronizationVSAvoidcomponent quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The temperature sensing member serves multiple functions: it detects film rotation status by monitoring temperature changes, and it also monitors the thermal state of the fixing film. This multi-functionality eliminates the need for separate rotation detection components, reducing device complexity while maintaining reliable heating synchronization.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the temperature changes that naturally occur during film rotation as the detection signal. The rotating film itself provides the detection mechanism through its thermal signature, eliminating the need for external rotation detection devices. The temperature sensing member simply monitors these natural thermal variations to determine rotation status.

Inventive Principle:

Principle #25Self-service

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 prevents deformation of the fixing film due to thermal stress while reducing warm-up time by detecting film rotation and adjusting heater power, using a simpler configuration compared to existing solutions.

Implementation Method 1

a heater that heats part of the film in the direction of rotation

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a temperature sensing member configured to sense a temperature of the inner surface of the film

Methodology Applied

Scientific EffectTemperature sensing: Thermistor

Data Source

PatentUS10496018B2Fixing apparatus

Publication Date: 2019.12.03 CANON KK

AI summary

In a warm-up period of a fixing apparatus of the present disclosure, a control unit supplies first electric power to a heater and thereafter supplies second electric power larger than the first electric power to the heater. The timing of starting to supply the second electric power is determined according to the degree of an increase in temperature sensed by a temperature sensing member after a driving signal is transmitted to a driving source.