Fixing Device Heating Element State Determination

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Solution Overview

Problem

The existing on-demand fixing method in image forming apparatuses leads to premature replacement of heating elements, resulting in waste and reduced yield, as individual heating elements cannot be replaced independently due to their shared substrate, causing improper image formation and reduced apparatus efficiency.

Innovation Solution

An image forming apparatus with a fixing device containing multiple heating elements arranged in the main scanning direction, utilizing a band-shaped thin film and a rotatable body to heat an inspection sheet with decolorable images of varying densities, allowing the control unit to determine the operational state of each heating element based on read images, enabling selective replacement or adjustment of failed elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plurality of heating elements are arranged on the same sheet substrate, then the heater unit can provide comprehensive heating coverage, but individual heating elements cannot be replaced independently when one fails

Engineering Contradiction:
Improveheating element functionalityVSAvoidheating element replacement
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The invention divides the heating element assembly into separable segments. Each heating element is mounted on its own separate substrate or can be independently detached from the common substrate, allowing individual replacement without replacing the entire heater unit. This segmentation enables maintenance of functional elements while replacing only the failed component.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The failed heating element is extracted or removed from the heater unit assembly independently. The design allows for the extraction of individual heating elements from the common substrate, enabling selective replacement of only the defective element while retaining the other functional heating elements on the substrate.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If heating elements are replaced before their service life ends to prevent improper image formation, then image quality is maintained, but operational heating elements are discarded causing waste

Engineering Contradiction:
Improveimage formation qualityVSAvoidfunctional heating element waste
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The system includes a determination device that automatically monitors and assesses the operational state of each heating element. By providing self-diagnosis capabilities, the system can identify which heating elements actually need replacement versus those that are still functional, enabling selective replacement and preventing premature disposal of serviceable elements.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The determination device provides feedback information about the operational status of each heating element. This feedback mechanism allows the system to make informed decisions about replacement timing, replacing only when necessary based on actual performance data rather than predetermined schedules, thus reducing waste of functional elements.

Inventive Principle:
Principle #23Feedback

3Reliability

If the entire heater unit is replaced when one heating element fails, then image formation reliability is maintained, but the yield and efficiency of the image forming apparatus is reduced

Engineering Contradiction:
Improveimage formation consistencyVSAvoidapparatus yield
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The heater unit is segmented into independently replaceable heating elements. When one element fails, only that specific segment needs replacement rather than the entire unit. This reduces downtime and maintains productivity by allowing the apparatus to continue operating with the remaining functional heating elements during the replacement process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of discarding the entire heater unit when one element fails, the system recovers and retains the functional heating elements on the substrate. Only the failed element is discarded and replaced, maximizing the utilization of existing components and maintaining apparatus yield.

Inventive Principle:
Principle #34Discarding and recovering

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 allows for the accurate determination of heating element states and potential corrections, extending the life of the heater unit, reducing waste, and improving the yield of the image forming apparatus by enabling the replacement or adjustment of only faulty heating elements while maintaining the functionality of others.

Implementation Method 1

The fixing device heats the plurality of heating elements when an inspection sheet is passed through the fixing device

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

an inspection sheet having plural images formed by using a developer that becomes decolored when subject to heating

Methodology Applied
Scientific EffectThermal decoloration: Thermochromism

Data Source

PatentEP3693799B1Image forming apparatus and determination method
Publication Date: 2022.09.14 TOSHIBA TEC KK
  • EP3693799B1 patent drawingFigure 1
  • EP3693799B1 patent drawingFigure 2
  • EP3693799B1 patent drawingFigure 3

AI summary

An image forming apparatus includes a fixing device, an image reading unit, and a control unit. The fixing device includes a heating elements arranged in a main scanning direction, a band-shaped thin film which slides on the surface of the heating element while in contact with the heating element, and a rotatable body configured to press against a surface of the thin film to cause the thin film to rotate. The fixing device heats the heating elements when an inspection sheet is passed through the fixing device, the inspection sheet having plural images formed by using a decolorable developer, each of the images having an image density that differs in a sub-scanning direction of the image forming apparatus. The image reading unit reads an image of the heated inspection sheet and the control unit determines an operative state of each heating element based on the read image. (Figure 1)