Fixing Unit Separation Mechanism for Accurate Heating Unit Replacement

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Solution Overview

Problem

Existing fixing units for image forming apparatuses require complex component arrangements and multiple processing steps to maintain the accuracy of separation members, complicating the replacement process and increasing costs.

Innovation Solution

A fixing unit design that includes a detachable heating unit, a guide mechanism for precise positioning, and a movable separation unit, allowing for simplified attachment and detachment without the need for additional jigs, thereby reducing the number of components and processing steps while maintaining positional accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the separation member is positioned and attached with high accuracy on the heating rotary member, then the separation function is improved, but the number of components and processing steps increases due to the need for additional jigs and assembly operations

Engineering Contradiction:

Improvepositional accuracy of separation memberVSAvoidnumber of components and processing steps

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The heating unit is designed with integrated guide portions that automatically guide the heating unit from the contact start position to the attachment position, enabling self-alignment and self-positioning without requiring external jigs or complex assembly operations. The separation member is positioned to contact the heating unit at the contact start position, and the heating unit's own movement mechanism serves to achieve precise positioning.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The guide portions are integrated into the casing structure, merging the guidance function with the housing. The separation member is integrated with the separation unit that can move relative to the casing, combining the separation function with the positioning mechanism. This integration reduces the need for separate components like jigs.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If the separation unit is arranged outside the heating unit, then the replacement cost of the heating unit is reduced, but the separation member may interfere with the heating unit replacement process

Engineering Contradiction:

Improvereplacement cost of heating unitVSAvoidheating unit replacement process

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The separation unit is designed to be movable relative to the casing, capable of moving between a first position (when heating unit is attached) and a second position (when heating unit is retracted). This dynamic positioning allows the separation member to clear the heating unit path during replacement while maintaining its functional position during operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The separation unit is positioned to retreat to the second position in advance before the heating unit is removed, preventing interference with the replacement process. The guide portions are designed to guide the heating unit to the contact start position where the separation member is already positioned to avoid interference.

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

The solution enables efficient and accurate attachment of the heating unit without interfering with the separation member, reducing the complexity and cost of component replacement while maintaining high positional accuracy for the separation member.

Implementation Method 1

a heating unit configured to be detachably attached to the casing and comprising a first rotary member configured to contact and heat the recording material

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a pressure rotary member configured to contact the first rotary member and form a fixing nip portion with the first rotary member for conveying the recording material

Methodology Applied

Scientific EffectPressure: Pressure Increase

Data Source

PatentUS11287766B2Fixing unit, image forming apparatus and image forming system

Publication Date: 2022.03.29 CANON KK

AI summary

A fixing unit includes a casing, a heating unit, a second rotary member, a first guide portion, a separation unit, and a separation unit movement mechanism. The separation unit has a separation member and movable relative to the casing between a first position at which the separation unit is positioned when the heating unit is positioned at a position to form a fixing nip portion, and a second position at which the separation unit is positioned when the heating unit is retracted from the position to form the fixing nip portion. The separation unit movement mechanism is configured to move the separation unit from the second position to the first position with the heating unit mounting to the position to form the fixing nip portion.