Dual-Heater Fixing Unit Control for Abnormal Temperature Rise

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Solution Overview

Problem

Existing electrophotographic image forming apparatuses face issues with abnormal energization states leading to rapid temperature rises and potential damage to fixing device components due to insufficient power control, especially in standby modes with slower rotation speeds.

Innovation Solution

The apparatus incorporates a dual-heater system with a control unit that manages power distribution between first and second heaters, allowing power to one heater in the fixing state and both in the standby state, and employs an exclusion unit to prevent simultaneous power supply to certain heaters, along with a rotation detection unit to manage power based on belt speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the power supply capacity is increased to support high-speed image forming, then productivity is improved, but the risk of abnormal energization and temperature rise increases

Engineering Contradiction:

Improveimage forming speedVSAvoidabnormal energization risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The power supply system is divided into multiple independent power supply units, each capable of supplying power to specific heaters. This segmentation allows selective power supply control, enabling the system to operate at high power levels when needed while maintaining the ability to isolate and control individual power sources to prevent abnormal energization and temperature rise.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If the rotation speed of the heating rotation member is reduced in standby mode to save energy, then use of energy is improved, but the temperature rise during abnormal energization increases

Engineering Contradiction:

Improvestandby mode energy consumptionVSAvoidtemperature rise during abnormal energization

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The system dynamically adjusts the rotation speed of the heating rotation member based on operational mode (standby vs. active). In standby mode, reduced rotation speed lowers energy consumption. In active mode, full rotation speed ensures adequate heat dissipation. The control system monitors operational state and automatically adjusts rotation speed to optimize both energy efficiency and thermal management.

Inventive Principle:

Principle #15Dynamics

3Productivity

If multiple halogen heaters are arranged on a roller with large heat capacity, then productivity is improved, but the complexity of power supply control increases

Engineering Contradiction:

Improvehigh-speed image forming capabilityVSAvoidpower supply system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control system incorporates feedback mechanisms to monitor the operational state of multiple heaters and the power supply system. This feedback enables intelligent decision-making regarding power distribution, allowing the system to optimize power allocation across multiple heaters while preventing abnormal energization, thus managing complexity through automated control rather than manual intervention.

Inventive Principle:

Principle #23Feedback

4Reliability

If the damage prevention mechanism detects abnormal heating and stops operation, then reliability is improved, but the temperature rise during the detection-to-stop period increases

Engineering Contradiction:

Improvedamage prevention capabilityVSAvoidtemperature rise during detection-to-stop period

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The control system continuously monitors temperature and power supply status before abnormal conditions fully develop. When potential abnormalities are detected, the system takes preliminary actions such as reducing power supply to affected heaters or adjusting rotation speed to enhance heat dissipation. This preliminary action reduces the temperature rise that occurs during the detection-to-stop period, complementing the damage prevention mechanism's stop operation function.

Inventive Principle:

Principle #10Preliminary 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 approach effectively suppresses temperature rises during abnormal energization, minimizing component damage and reducing the risk of overheating, thereby extending the lifespan of the fixing unit and reducing maintenance costs.

Implementation Method 1

a heat source configured to heat the heating rotation member, the heat source including a first heater and a second heater

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a heating rotation member configured to heat a recording medium

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12510852B2Image forming apparatus

Publication Date: 2025.12.30 CANON KK

AI summary

An image forming apparatus includes: a heating unit including a heating rotation member configured to heat a recording medium: a pressure rotation member which contacts the heating rotation member to form a nip portion to fix a toner image to the recording medium, a heat source configured to heat the heating rotation member, the heat source including a first heater and a second heater, and a control unit configured to control the first heater and the second heater, wherein the image forming unit is operable to transition to: a fixing state in which an operation to fix the toner image to the recording medium is performed by receiving a job; and a standby state, to wait for the job, in which an operation to fix the toner image to the recording medium is not performed.