Developer Conveying Screw Geometry for Compact Image Forming

Solution Overview

Problem

Existing image forming apparatuses face challenges in efficiently conveying developer within developing devices due to the design of conveying screws, leading to potential issues with developer circulation and distribution, which can affect image quality and device size.

Innovation Solution

The developing device incorporates a first conveying screw and a second conveying screw with specific shaft diameters and configurations, including tapered sections, to create a circulation path that enhances developer conveyance and distribution, reducing the horizontal size of the device while maintaining efficient developer flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional conveying screw design is used, then device structure is simple, but developer circulation and distribution efficiency deteriorates

Engineering Contradiction:

Improvedeveloper circulation efficiencyVSAvoidconveying screw structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The conveying screw is divided into multiple sections along its axial direction, with each section having a different shaft diameter. The first section has a larger shaft diameter to provide strong conveying force, while the second section has a smaller shaft diameter to reduce resistance and facilitate smooth developer flow. This segmentation allows the screw to perform different functions in different regions, improving overall circulation efficiency without requiring multiple separate components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the conveying screw are designed with locally optimized properties. The first section near the developer supply area has a larger diameter to effectively push and circulate developer, while the second section has a smaller diameter to reduce friction and allow easy developer entry/exit. This local quality variation ensures that each part of the screw is optimized for its specific function in the circulation path.

Inventive Principle:

Principle #3Local quality

2Force

If larger conveying screw diameter is used, then developer conveyance force is improved, but device horizontal size increases

Engineering Contradiction:

Improvedeveloper conveyance forceVSAvoiddevice horizontal size

Core Design Contradiction:

ForceVSLength of stationary object

Solution Approach 1:

The conveying screw is divided into multiple sections along its axial direction, with each section having a different shaft diameter. The first section has a larger shaft diameter to provide strong conveying force, while the second section has a smaller shaft diameter to reduce resistance and facilitate smooth developer flow. This segmentation allows the screw to perform different functions in different regions, improving overall circulation efficiency without requiring multiple separate components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a uniformly large diameter screw that would increase horizontal device size, the invention varies the diameter along the axial dimension. This dimensional variation allows the screw to provide strong conveying force where needed (larger diameter section) while maintaining a compact overall profile (smaller diameter section), thus improving conveyance force without proportionally increasing device horizontal size.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If uniform shaft diameter is used, then manufacturing is simplified, but developer flow resistance increases

Engineering Contradiction:

Improveconveying screw manufacturingVSAvoiddeveloper flow resistance

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The conveying screw is divided into multiple sections along its axial direction, with each section having a different shaft diameter. The first section has a larger shaft diameter to provide strong conveying force, while the second section has a smaller shaft diameter to reduce resistance and facilitate smooth developer flow. This segmentation allows the screw to perform different functions in different regions, improving overall circulation efficiency without requiring multiple separate components.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12498652B2Developing device, process cartridge, and image forming apparatus

Publication Date: 2025.12.16 RICOH CO LTD

AI summary

A developing device includes a developer bearer, a first conveying screw conveying developer from one end to another end of a first conveyance path in a first direction, a second conveying screw conveying the developer in a direction opposite to the first direction in a second conveyance path, and a partition having a first communication port communicating the one end of the first conveyance path and the second conveyance path. A shaft diameter of the first conveying screw from one end to a position away from the first communication port by a first predetermined distance is smaller than a shaft diameter of another portion of the first conveying screw. A shaft diameter of the second conveying screw from one end to a position away from the first communication port by a second predetermined distance is larger than a shaft diameter of another portion of the second conveying screw.