Developing Device Scraper Position for Toner Concentration Stability

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Solution Overview

Problem

In image forming apparatuses using two-component developers, maintaining accurate toner concentration sensing is challenging due to developer circulation and stirring mechanisms, leading to potential image fogging and uneven toner supply.

Innovation Solution

A developing device with a partitioned developing container, dual stirring conveyance members, and a scraper positioned to prevent developer compression near the toner concentration sensor, ensuring accurate toner concentration measurement and preventing image fogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single stirring conveyance member is used to circulate developer, then the structure is simple, but the toner concentration becomes uneven leading to image fogging

Engineering Contradiction:

Improvestirring conveyance structureVSAvoidtoner concentration uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The developing container is divided into a first conveyance chamber and a second conveyance chamber by a partition wall. The first stirring conveyance member operates in the first chamber while the second stirring conveyance member operates in the second chamber. This segmentation allows independent control of stirring operations in each chamber, preventing toner concentration unevenness and image fogging while maintaining manageable structural complexity.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If the scraper is positioned at the intersection of conveyance blades, then it effectively cleans the sensor, but it compresses the developer causing toner concentration variation

Engineering Contradiction:

Improvesensor cleaning effectivenessVSAvoidtoner concentration stability

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The scraper is positioned at a specific location that is not at the intersection of the first and second conveyance blades. This localized positioning avoids the compression zone created by blade intersections while still maintaining effective contact with the toner concentration sensor for cleaning. The scraper's position is optimized to balance cleaning effectiveness with minimal disturbance to developer flow and toner concentration.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If toner is supplied to increase concentration, then toner supply accuracy improves, but uneven distribution causes image fogging

Engineering Contradiction:

Improvetoner concentrationVSAvoidtoner distribution uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The first and second stirring conveyance members continuously circulate and mix the developer in their respective chambers. This continuous stirring action ensures that when toner is supplied to adjust concentration, it is immediately and uniformly distributed throughout the developer. The continuous circulation prevents localized toner accumulation and ensures homogeneous toner distribution, eliminating image fogging while maintaining accurate toner supply.

Inventive Principle:

Principle #20Continuity of useful 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 stabilizes toner concentration sensing, reduces image fogging, and maintains consistent toner supply, enhancing the overall image forming process.

Implementation Method 1

a first conveyance blade that is formed on an outer circumferential surface of the rotary shaft and is caused by rotation of the rotary shaft to convey the developer in the first direction, and a second conveyance blade that is formed on the outer circumferential surface of the rotary shaft so as to overlap with a region in which the first conveyance blade is formed, has the opposite phase to the first conveyance blade

Methodology Applied

Scientific EffectOpposite phase rotation:

Implementation Method 2

The scraper is arranged substantially parallel to the rotary shaft at a position shifted in an axial direction from intersections between the first conveyance blade and the second conveyance blade, and the scraper has a phase of 45° to 135° with respect to the closest one of the intersections on an upstream side in the first direction

Methodology Applied

Scientific EffectMechanical scraping:

Data Source

PatentUS11650521B2Developing device and image forming apparatus including the same

Publication Date: 2023.05.16 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

A developing device includes a developing container, a first stirring conveyance member, a second stirring conveyance member, a developer carrying member, a toner concentration sensor, and a scraper. The first stirring conveyance member includes a rotary shaft, a first conveyance blade that is formed on an outer circumferential surface of the rotary shaft and conveys a developer in a first direction, and a second conveyance blade that has the opposite phase to the first conveyance blade and has a lower radial height than the first conveyance blade. The scraper is arranged substantially parallel to the rotary shaft at a position shifted in an axial direction from intersections between the first conveyance blade and the second conveyance blade and has a phase of 45° to 135° with respect to the closest one of the intersections on an upstream side in the first direction.