Fixing Device Temperature Control via Non-Contact Detection

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses face inaccuracies in temperature control due to errors in temperature detection caused by radiation and convection heat from external heating sources, leading to inefficient toner fixation on recording media.

Innovation Solution

The implementation of a temperature detecting device positioned to avoid direct contact with the external heating roll, combined with a cleaning device to minimize interference from radiation and convection heat, and a refresh roll to polish the heating roll surface, ensuring accurate temperature control and image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature detecting device is positioned to face the external circumferential surface of the second rotating member, then temperature detection is enabled, but radiation and convection heat from the heating device cause detection errors

Engineering Contradiction:

Improvetemperature detection accuracyVSAvoidradiation and convection heat interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A tabular member (shield) is introduced as an intermediary between the heating device and the temperature detecting device. This shield blocks the direct path of radiation and convection heat from the heating device to the temperature sensor, eliminating the harmful thermal interference while allowing the sensor to detect the actual temperature of the second rotating member's surface through non-contact measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the cleaning device is disposed between the heating device and the temperature detecting device, then the heating device surface is cleaned, but the temperature detecting device may be affected by cleaned particles

Engineering Contradiction:

Improveheating device performanceVSAvoidcleaned particles interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The cleaning operation is extracted and performed separately from the temperature detection zone. The cleaning device is configured to clean the heating device surface in a location that does not interfere with the temperature detecting device's line of sight to the second rotating member, thus removing the source of cleaned particles from the detection path.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the temperature detecting device does not contact the external circumferential surface, then contamination is prevented, but measurement accuracy may be reduced

Engineering Contradiction:

Improvedetection device contamination resistanceVSAvoidtemperature measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The mechanical contact-based temperature measurement system is replaced with a non-contact temperature detecting device (such as an infrared sensor). This substitution eliminates the need for physical contact between the detector and the second rotating member's surface, preventing contamination of the detection device while maintaining accurate temperature measurement through optical or electromagnetic radiation detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration enhances the accuracy of temperature control, reducing errors in toner fixation and maintaining image quality by blocking radiation and convection heat, thus improving the overall performance of the fixing device.

Implementation Method 1

a heating device whose circumferential surface circularly moves while contacting an external circumferential surface of the second rotating member, the heating device heating the second rotating member

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a temperature detecting device that is disposed to face the external circumferential surface of the second rotating member without contacting the external circumferential surface and detects temperature of the external circumferential surface

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

a cleaning device that cleans the circumferential surface of the heating device

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8509666B2Fixing device and image forming apparatus

Publication Date: 2013.08.13 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A fixing device includes: a first rotating member; a second rotating member that extends along the first rotating member, sandwiches a recording medium with a toner image formed thereon between the first and second rotating members, rotates together with the first rotating member, and heats the recording medium to fix the toner image on the recording medium; a heating device whose circumferential surface circularly moves while contacting an external circumferential surface of the second rotating member, and the heating device heats the second rotating member; a temperature detecting device disposed to face the external circumferential surface of the second rotating member without contacting the external circumferential surface to detect a temperature thereof; and a cleaning device cleaning the circumferential surface of the heating device and disposed between the heating device and the temperature detecting device along the surface of the second rotating member.