Toner Developing Unit With Capacitance Sensing Stability

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Solution Overview

Problem

Conventional electrophotographic image forming apparatuses face challenges in accurately sensing the remaining toner amount due to instability when the toner amount is low, leading to potential spilling and inaccurate calculations.

Innovation Solution

The developing apparatus incorporates a conveying member with a flexible sheet connected to a shaft, and a sensing portion with first and second conducting members, where the first inner wall face is oriented downward and the second inner wall face is inclined at an angle greater than the angle of repose of the developer, ensuring stable toner conveyance and precise electrostatic capacitance sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the stirring member is in a horizontal orientation when passing through the remaining amount sensing portion, then the conveying member can effectively convey toner, but part of the toner spills off the stirring member from the distal end side toward the rotation shaft side, causing unstable sensing results

Engineering Contradiction:

Improvetoner conveying efficiencyVSAvoidremaining toner amount sensing precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional horizontal orientation of the stirring member to a substantially vertical orientation when passing through the remaining amount sensing portion. This inversion prevents toner spillage from the distal end toward the rotation shaft side, ensuring stable toner amount sensing while maintaining effective conveying functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If the remaining toner amount is small, then the sensing precision should be higher to notify users accurately, but the toner amount pressed into the sensing portion becomes unstable due to spillage

Engineering Contradiction:

Improveremaining toner amount sensing precisionVSAvoidstability of remaining toner amount calculation

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

By inverting the stirring member orientation to substantially vertical when passing through the sensing portion, the patent eliminates toner spillage that causes instability. This ensures that even when remaining toner amount is small, the toner amount pressed into the sensing portion remains stable and reliable for accurate sensing.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the orientation parameter of the stirring member from horizontal to substantially vertical when passing through the remaining amount sensing portion. This parameter change prevents toner spillage and ensures stable sensing results, particularly when the remaining toner amount is small and sensing precision is critical.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the stirring member conveys toner while being close to horizontal, then the conveying function is maintained, but toner spillage occurs reducing sensing accuracy

Engineering Contradiction:

Improveconveying functionVSAvoidtoner amount sensing accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent inverts the stirring member orientation from horizontal to substantially vertical when passing through the remaining amount sensing portion. This inversion maintains the conveying function while preventing toner spillage, thereby ensuring accurate sensing of the remaining toner amount.

Inventive Principle:

Principle #13The other way round (Inversion)

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 improves the precision of remaining developer amount sensing by minimizing toner spillage and enhancing stability during low toner conditions, resulting in accurate toner level detection.

Implementation Method 1

a sensing portion that includes a first conducting member and a second conducting member provided in the accommodation portion, wherein the sensing portion is configured to sense electrostatic capacitance, in accordance with an amount of developer, between the first conducting member and the second conducting member

Methodology Applied

Scientific EffectElectrostatic capacitance sensing: Capacitance

Implementation Method 2

the second inner wall face is oriented upward and also has an inclination angle that is greater than or equal to an angle of repose of the developer

Methodology Applied

Scientific EffectAngle of repose: Angle of Repose

Data Source

PatentUS20250306504A1Developing apparatus

Publication Date: 2025.10.02 CANON KK

AI summary

A developing apparatus includes an accommodation portion for developer, a conveying member with a rotating shaft and sheet for conveying developer, and a sensing portion with first and second conducting members for sensing electrostatic capacitance based on developer amount. An accommodation portion frame body features a recessed portion with intersecting first and second inner wall faces bearing the conducting members. The recessed portion extends from an inner side of the accommodation portion toward an outer side. During image formation, the first inner wall faces downward while the second inner wall faces upward with an inclination angle exceeding the developer's angle of repose. The intersection line of imaginary lines passing through these wall faces lies below the rotation axis line.