Liquid Developer End Portion Restricting Member Contact Angle

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Solution Overview

Problem

Existing developing devices in image forming apparatuses face challenges in preventing the movement of developing liquid around the end portion, leading to potential liquid leakage and image defects.

Innovation Solution

A developing device is designed with an end portion restricting member that contacts the developer carrying member at its end, restricting the movement of the liquid developer in the rotational axis direction. The contact angle of the side surface of the end portion restricting member with the liquid developer is set to 45° or more.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a heat source is added to prevent carrier liquid movement by heating and vaporization, then liquid leakage is prevented, but the number of component parts increases

Engineering Contradiction:
Improveliquid leakage preventionVSAvoidnumber of component parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention changes the surface property parameter of the end portion restricting member by controlling its contact angle with the carrier liquid to be 45° or more. This parameter change creates repulsion between the member surface and the carrier liquid, preventing liquid movement without requiring additional heating components, thus resolving the contradiction between reliability improvement and device complexity increase

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the thermal field approach (heat source for vaporization) with a surface property approach (contact angle control). By substituting the mechanical/thermal system with a surface chemistry approach, the invention achieves liquid leakage prevention without adding heat generation components, thereby reducing device complexity while maintaining reliability

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

2Reliability

If the contact angle of the end portion restricting member with the liquid developer is increased to 45° or more, then liquid movement is reduced, but the surface treatment complexity increases

Engineering Contradiction:
Improveliquid movement restrictionVSAvoidsurface treatment
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention specifies a quantitative parameter range (contact angle of 45° or more) for the end portion restricting member surface. This clear parameter specification enables standardized manufacturing and quality control, preventing liquid developer movement effectively while avoiding overly complex surface treatment processes through defined performance criteria

Inventive Principle:
Principle #35Parameter changes

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 configuration effectively reduces the movement of the developing liquid around the end portion, preventing liquid leakage and image defects while maintaining a simple device constitution.

Implementation Method 1

a contact angle of a side surface of the end portion restricting member on a side where the developer carrying member carries the liquid developer, to the liquid developer is 45° or more

Methodology Applied
Scientific EffectContact angle: Wetting

Data Source

PatentEP3605242B1Developing device, cleaning device, and liquid developer device
Publication Date: 2025.05.07 CANON KK
  • EP3605242B1 patent drawingFigure 1
  • EP3605242B1 patent drawingFigure 2~3
  • EP3605242B1 patent drawingFigure 4~5

AI summary

A developing device includes a developer carrying member (41) rotating while carrying a liquid developer on a carrying surface (41b) and an end portion restricting member (46) for restricting movement of the liquid developer, carried on the carrying surface (41b), to an outside of the carrying surface (41b). A contact angle between the end portion restricting member (46) and the liquid developer is set so as to be larger than a contact angle between the carrying surface (41b) of the developer carrying member (41) and the liquid developer. By this, when the developer carrying member (41) is separated from the end portion restricting member (46), deposition of the liquid developer in a large amount in the neighborhood of an end (41c) of the carrying surface (41b) is prevented.