Conveyance Screw Rib and Blade Geometry for Developer Bulk Density
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Solution Overview
Problem
Existing developing apparatuses using two-component developers face challenges in stabilizing bulk density due to variations in rotational speed of the conveyance screw, which affects the accuracy of toner density measurement by inductance sensors.
Innovation Solution
A developing apparatus with a conveyance screw featuring a shaft, a first helical blade, a radial rib, and a second blade portion that extends not more than one-third of a turn from the rib's upstream end, stabilizes bulk density and improves toner density measurement accuracy by maintaining consistent developer conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveyance screw rotates at variable speeds, then productivity is improved, but bulk density stability deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the conveyance screw, specifically the extension length of the second blade portion (controlling it to not more than one-third of a turn from the upstream end of the rib), to maintain consistent bulk density across different rotational speeds. This parameter optimization ensures that the blade portion effectively controls developer flow and prevents density variation regardless of speed changes.
2Productivity
If the conveyance screw rotates at variable speeds, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
By optimizing the geometric parameter of the second blade portion extension length (not more than one-third of a turn), the patent ensures that toner density measurements remain accurate even when conveyance speed varies. This configuration stabilizes the developer flow pattern, allowing the inductance sensor to consistently measure toner density without interference from speed-induced bulk density fluctuations.
3Productivity
If the second blade portion extends more than one-third of a turn, then conveyance efficiency is improved, but bulk density stability deteriorates
Solution Approach 1:
The patent identifies and optimizes the critical parameter of the second blade portion extension length, setting it to not more than one-third of a turn from the upstream end of the rib. This specific parameter range achieves the optimal balance between conveyance efficiency and bulk density stability, preventing over-conveyance that would cause density variation while maintaining effective developer transport.
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 effectively stabilizes bulk density and enhances the accuracy of toner density measurement, regardless of conveyance screw speed variations, ensuring consistent image quality in electrophotographic systems.
Implementation Method 1
an inductance sensor arranged to oppose a portion, in a circumferential direction, of the conveyance screw and configured to detect toner density of the developer accommodated in the developer container
Implementation Method 2
a first blade portion comprising a helical shape, the first blade portion being configured to rotate integrally with the shaft portion and convey the developer accommodated in the developer container in a conveyance direction by rotation
Data Source
AI summary
According to a first aspect of the present invention, a developing apparatus includes a developer container, a conveyance screw, and an inductance sensor. The conveyance screw further comprises a rib, protruding in a radial direction from the shaft portion, provided at a position opposed to the inductance sensor, and a second blade portion provided continuously to an upstream end portion of the rib with respect to the conveyance direction and configured to convey the developer to the conveyance direction by rotation. The second blade portion is formed to extend not more than one-third of a turn from the upstream end portion of the rib downstream in a direction of rotation of the conveyance screw when viewed in an axial direction of the conveyance screw.