Cartridge Attachment Guide Rails Prevent Unauthorized Insertion

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Solution Overview

Problem

Existing electrophotographic image forming apparatuses face challenges in reliably determining whether a cartridge is authorized for attachment, leading to potential attachment errors.

Innovation Solution

The implementation of a simple configuration that utilizes guide rails and movable levers to differentiate between authorized and unauthorized cartridges based on specific engagement and positioning features, preventing unauthorized cartridges from being inserted by regulating their attachment path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a movable base with engagement portion is used to prevent unallowed cartridge attachment, then attachment error prevention is improved, but device complexity increases

Engineering Contradiction:
Improveattachment error preventionVSAvoidmovable base mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cartridge is divided into multiple functional components: a body portion containing the image forming elements, and a separate engagement prevention portion with protrusions that extend in the insertion direction. This segmentation allows the engagement prevention function to be integrated into the cartridge structure without requiring complex movable mechanisms in the image forming apparatus.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of having the image forming apparatus actively prevent unauthorized cartridge attachment through movable bases or detection mechanisms, the invention inverts the approach by having the cartridge itself passively prevent attachment through its engagement prevention portion. The protrusions on the cartridge body directly interfere with the attachment path, eliminating the need for complex active prevention mechanisms in the apparatus.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If multiple abutting portions and movable members are used to identify authorized cartridges, then identification reliability is improved, but ease of operation deteriorates

Engineering Contradiction:
Improvecartridge identificationVSAvoidcartridge insertion
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The identification function is segmented into passive geometric features (protrusions and recesses) on the cartridge body rather than requiring active detection mechanisms. The engagement prevention portion with its specific protrusion pattern serves as the identification element, simplifying the interaction between user and apparatus.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cartridge's engagement prevention portion with protrusions automatically performs the identification function during insertion. The geometric features self-align with corresponding recesses in the apparatus, providing automatic verification of authorized cartridge type without requiring separate detection steps or complex movable members.

Inventive Principle:
Principle #25Self-service

3Reliability

If guide portions with gaps are used to control protruding portion passage, then attachment control is improved, but device complexity increases

Engineering Contradiction:
Improveattachment controlVSAvoidguide portion structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The attachment control function is extracted from the apparatus and transferred to the cartridge itself. The engagement prevention portion with protrusions on the cartridge body performs the attachment control that would otherwise require complex guide portions and gap structures in the apparatus. This extraction simplifies the apparatus structure while maintaining reliable attachment control.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3674814B1Image forming apparatus, and apparatus body thereof
Publication Date: 2024.12.11 CANON KK
  • EP3674814B1 patent drawingFigure 1A
  • EP3674814B1 patent drawingFigure 1B
  • EP3674814B1 patent drawingFigure 1C

AI summary

An apparatus body of an image forming apparatus has a first guide portion having an inlet shape corresponding to an outer shape of an engagement portion provided in a cartridge when seen in an attachment direction of the cartridge to the apparatus body and guiding the engagement portion, a second guide portion for guiding a positioning target portion which is provided on the cartridge for positioning an attachment completion position of the cartridge with respect to the apparatus body, and a movable member being at a regulation position at which a guiding path of the positioning target portion by the second guide portion is blocked is immovable from the regulation position unless being pressed by the engagement portion.