Fixing Unit Temperature Control Using Medium Bend Detection

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Solution Overview

Problem

Existing image forming apparatuses face issues with fixing errors due to inaccurate control of fixing temperature based on medium type detection methods that rely on reflectance or transmittance, leading to inefficiencies and increased costs.

Innovation Solution

Incorporating a bend detector upstream from the fixing member to detect medium bends, with a heating control member that adjusts the fixing temperature based on detected bends, and using guide members to facilitate medium alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fixing temperature is controlled based on medium type detection using reflectance or transmittance, then medium type can be identified, but fixing errors increase and costs increase

Engineering Contradiction:
Improvemedium type detection accuracyVSAvoidfixing accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces optical detection methods (reflectance/transmittance) with a mechanical detection method. A bend detector mechanically senses the curvature of the medium as it passes through the fixing device, converting physical deformation into detection signals that trigger appropriate fixing temperature adjustments, thereby eliminating fixing errors associated with optical methods

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the detection parameter from optical properties (reflectance/transmittance) to mechanical property (bend/curvature). By detecting the physical bending of the medium during transport through the fixing device, the system directly identifies medium type characteristics that correlate with fixing requirements, enabling more accurate temperature control

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If fixing temperature is controlled based on medium type detection using reflectance or transmittance, then medium type can be identified, but costs increase

Engineering Contradiction:
Improvemedium type detection accuracyVSAvoiddevice cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs a simple, low-cost bend detector mechanism that can be manufactured inexpensively compared to optical sensors. The mechanical detection system uses basic components like levers, springs, or capacitive sensors that detect medium bend, providing a cost-effective solution that maintains detection accuracy while reducing overall device cost

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By substituting expensive optical detection systems with a simple mechanical bend detection system, the patent achieves medium type identification at lower cost. The mechanical approach uses straightforward physical principles that require less sophisticated (and therefore less expensive) components while maintaining functional effectiveness

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a bend detector is introduced to detect medium bends, then fixing temperature control accuracy improves, but device complexity increases

Engineering Contradiction:
Improvefixing temperature control accuracyVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential detection function needed for fixing temperature control - medium bend detection. By focusing solely on detecting the curvature of the medium during transport and linking this directly to temperature adjustment, the system achieves high reliability without incorporating unnecessary detection mechanisms, keeping the overall system relatively simple

Inventive Principle:
Principle #2Taking out (Extraction)

4Manufacturing precision

If guide members are added to facilitate medium alignment, then medium positioning accuracy improves, but device complexity increases

Engineering Contradiction:
Improvemedium positioning accuracyVSAvoidguide system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses guide members with curved surfaces that naturally guide the medium into proper alignment as it enters the fixing device. The curved geometry passively directs the medium path without requiring active control mechanisms, achieving improved positioning accuracy through simple geometric design rather than complex mechanical systems

Inventive Principle:
Principle #14Spheroidality (Curvature)

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

Reduces fixing errors by accurately controlling the fixing temperature based on medium bends, thereby enhancing the reliability and efficiency of the image forming process while minimizing costs.

Implementation Method 1

a heater that generates heat in accordance with a predetermined fixing temperature to fix an unfixed image held on a medium

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

a bend detector that is disposed upstream from the fixing member in a medium transport direction to detect a bend of a medium having a leading end arriving at the fixing member

Methodology Applied
Scientific EffectBend detection:

Data Source

PatentEP4682639A1Image forming apparatus
Publication Date: 2026.01.21 FUJIFILM BUSINESS INNOVATION CORP
  • EP4682639A1 patent drawingFigure 1
  • EP4682639A1 patent drawingFigure 2
  • EP4682639A1 patent drawingFigure 3

AI summary

An image forming apparatus includes a fixing member that includes a heater that generates heat in accordance with a predetermined fixing temperature to fix an unfixed image held on a medium, a bend detector that is disposed upstream from the fixing member in a medium transport direction to detect a bend of a medium having a leading end arriving at the fixing member, and a heating control member that controls the heater based on the bend of the medium detected by the bend detector.