Fixing Device Movable Member Positioning Guide

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses face challenges in accurately positioning a movable member with a flag portion between a light emitting and receiving portion during assembly, leading to potential contact with the photointerrupter and peripheral components, which can result in deformation or breakage, and require expensive automatic machines for stable assembly.

Innovation Solution

A fixing device design featuring a movable member with a contact portion and flag portion that can move relative to a light emitting and receiving portion, supported by side plates and a holding portion with a slit and projected portions, allowing precise positioning and assembly without overlapping with the detecting portion, enabling accurate alignment and assembly without unintentional contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tilt assembling is used to assemble the sensor flag, then the sensor flag can be assembled without contact with the photointerrupter and casing, but the sensor flag may unintentionally contact the photointerrupter and peripheral component parts when moving along a locus other than the proper locus during mounting

Engineering Contradiction:
Improveassembly reliabilityVSAvoidunintentional contact damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a guide structure consisting of a guide hole and guide protrusion as an intermediary mechanism between the sensor flag and the photointerrupter. This guide structure mediates the assembly process by constraining the movement path of the sensor flag, ensuring it follows the correct locus and preventing unintentional contact with peripheral components while maintaining the benefits of tilt assembling.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide structure is pre-configured in the assembly fixture or device housing before the sensor flag is assembled. This preliminary arrangement of the guide hole and guide protrusion establishes the correct movement path in advance, allowing the sensor flag to be guided along the proper locus during assembly, thereby preventing contact damage before it can occur.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If automatic machines are used for assembling the sensor flag with tilt assembling, then stable assembly can be achieved, but expensive automatic machines such as robot arms are required

Engineering Contradiction:
Improveassembly stabilityVSAvoidautomatic machine cost
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The guide structure enables the assembly system to self-correct and self-guide the sensor flag during assembly. By incorporating the guide hole and guide protrusion, the system provides its own positioning and alignment functions, eliminating the need for expensive external guidance systems or complex robotic control, thereby achieving stable assembly with simpler, more cost-effective equipment.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The guide structure acts as a mechanical intermediary that simplifies the automatic assembly process. Instead of requiring complex robotic manipulation for tilt assembling, the guide hole and guide protrusion provide a straightforward mechanical constraint that guides the sensor flag along the correct path, enabling stable assembly with less expensive automatic assembly equipment.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If the photo-interrupter is disposed inside the fixing device casing, then the ambient temperature is relatively low, but the heat-resistant property of the electric substrate may be compromised

Engineering Contradiction:
Improveambient temperatureVSAvoidheat-resistant property
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The opening in the casing serves as an intermediary structure that allows the photointerrupter to be positioned in a thermally favorable location while maintaining structural integrity. By providing this controlled opening, the design enables the photointerrupter to operate in a lower temperature environment outside the main fixing device casing, protecting the electric substrate from excessive heat while maintaining the necessary mechanical strength and rigidity of the casing.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design allows for accurate positioning of the movable member relative to the detecting portion, minimizing the risk of contact with peripheral components and enabling assembly using less expensive automatic machines, thereby enhancing the strength and rigidity of the fixing device while preventing deformation and breakage.

Implementation Method 1

a sensor flag including a rotatable flag portion and a photo-interrupter switched in logic by light transmission/light blocking with the flag portion

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

a photo-interrupter switched in logic by light transmission/light blocking with the flag portion

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS10768569B2Fixing device and image forming apparatus
Publication Date: 2020.09.08 CANON KK
  • US10768569B2 patent drawing
  • US10768569B2 patent drawing
  • US10768569B2 patent drawing

AI summary

A fixing device includes first and second rotatable members; a movable member; a first supporting side plate including an opening; a second supporting side plate; a detecting portion; a supporting plate; a holding portion; a slit portion; a first projected portion; a second projected portion; and a hole. When the position of the holding portion with respect to the height direction is regulated by the second projected portion in contact with the supporting plate, in a projection plane in which the outside of the first supporting side plate is viewed in the longitudinal direction of the first rotatable member, the flag portion is accommodated inside the opening and is in a non-overlapping position with the detecting portion. When the projected portion is engaged in the hole, in the projection plane, the flag portion is in an overlapping position with the detecting portion.