Electrophotographic Cartridge Spacing for Developing Roller Protection

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Solution Overview

Problem

Conventional electrophotographic image forming apparatuses face issues such as developer unevenness, contamination of recording materials, and accelerated deterioration of developing rollers due to prolonged contact between the developing roller and photosensitive drum, which existing solutions have not adequately addressed.

Innovation Solution

A cartridge design that includes a mechanism to space the developing roller from the photosensitive drum during non-developing periods, using movable members and spacers to control the contact and separation, ensuring minimal contact time to prevent deformation and contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the developing roller is kept in contact with the photosensitive drum during non-developing periods, then the developing roller can maintain its position, but the elastic layer becomes deformed causing image defects

Engineering Contradiction:
Improveposition stability of developing rollerVSAvoidimage quality uniformity
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies a movable spacer that can dynamically adjust its position between the developing roller and photosensitive drum. During developing operations, the spacer moves to allow contact between the developing roller and photosensitive drum for proper development. During non-developing periods, the spacer moves to separate them, preventing deformation of the elastic layer while maintaining position stability through the movable design rather than fixed contact.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the developing roller contacts the photosensitive drum during non-developing periods, then position stability is maintained, but developer is unnecessarily deposited on the drum and recording material

Engineering Contradiction:
Improveposition stability of developing rollerVSAvoiddeveloper contamination
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The movable spacer dynamically separates the developing roller from the photosensitive drum during non-developing periods, preventing unnecessary developer deposition on the drum and recording material while maintaining position stability through the dynamic adjustment capability of the spacer mechanism.

Inventive Principle:
Principle #15Dynamics

3Stability of the object's composition

If the developing roller and photosensitive drum are in contact for long periods during non-developing times, then position stability is maintained, but the developing roller and developer deteriorate accelerated

Engineering Contradiction:
Improveposition stability of developing rollerVSAvoidcomponent lifespan
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The movable spacer provides dynamic separation between the developing roller and photosensitive drum during non-developing periods, reducing prolonged contact that would accelerate deterioration of the developing roller and developer, thereby extending component lifespan while maintaining position stability through the movable design.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4350447B1Electrophotographic image forming device and cartridge
Publication Date: 2025.08.20 CANON KK
  • EP4350447B1 patent drawingFigure 1
  • EP4350447B1 patent drawingFigure 2
  • EP4350447B1 patent drawingFigure 3

AI summary

[Problem to be solved] To further develop a prior art cartridge. [Solution] A cartridge includes a holding movable between a first position for stably holding a second unit in a spaced position by a first unit and a second position, and a contact force receiving portion capable of receiving a contact force for moving the holding portion from the first position toward the second position to move the second unit to a developing position, when the second unit is in the spaced position. When a predetermined tangential line is a tangential line of a surface of a photosensitive member at an intersection, which is more remote from a rotational center of a charging member, of intersections between a line connecting a rotational center of the charging member and a rotational center of the photosensitive member and the surface of the photosensitive member, as viewed along a direction of a rotational axis of the developing member, and the cartridge is divided by the predetermined tangential line into sections, a predetermined section is a section in which the rotational center of the charging member does not exist, and as viewed along the rotational axis of the developing member when the second unit is in the spaced position, the contact force receiving portion is in the predetermined section.