Conveyance Screw with Variable Helical Blade Widths
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Solution Overview
Problem
Existing conveyance screws in developing apparatuses fail to achieve both highly efficient conveyance and agitation of developer simultaneously, particularly in downsized systems with limited developer amounts, leading to inefficient toner replenishment and density uniformity.
Innovation Solution
A conveyance screw with a shaft member featuring alternating wide and narrow helical blades, where the narrow portions have a smaller outer diameter than the wide portions, and are arranged to overlap partially in the axial direction, enhancing both conveyance and agitation performance by preventing developer stagnation and maintaining efficient mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional conveyance screw with uniform helical blades is used, then the structure is simple and easy to manufacture, but the developer conveyance efficiency and agitation efficiency cannot be simultaneously optimized
Solution Approach 1:
The helical blade is segmented into multiple sections along the axial direction, with each section having different radial widths. This segmentation allows the blade to perform different functions at different locations: wider sections for conveyance and narrower sections for agitation, thereby simultaneously improving both conveyance efficiency and agitation efficiency without requiring multiple separate components
Solution Approach 2:
Different sections of the helical blade are designed with different local qualities (radial widths) to optimize specific functions. The wider sections provide greater surface area for effective developer conveyance, while the narrower sections create stronger shear forces for intensive agitation. This local differentiation resolves the contradiction by making each part of the blade specialized for its intended function
2Volume of moving object
If the amount of developer stored in the developing apparatus is reduced for downsizing, then the apparatus size is reduced, but the efficiency of toner replenishment and density uniformity deteriorates
Solution Approach 1:
The conveyance screw with variable radial width blades creates dynamic flow patterns in the limited developer volume. The alternating wide and narrow sections generate pulsating agitation effects as the screw rotates, which enhances mixing efficiency and toner replenishment performance even when the total developer amount is small, thereby maintaining productivity in a compact apparatus
3Productivity
If a multithread screw with multiple helical blades is used, then the conveyance efficiency is improved, but the agitation efficiency and toner density uniformity are compromised
Solution Approach 1:
Each helical blade is segmented into wide and narrow sections that work in complementary fashion. The wide sections ensure efficient developer conveyance along the axial direction, while the narrow sections create intense local agitation through increased shear rates. This segmentation within each blade allows simultaneous achievement of both conveyance efficiency and toner density uniformity
Solution Approach 2:
The asymmetric design of helical blades with varying radial widths creates non-uniform flow patterns that enhance mixing. The alternating wide and narrow sections generate turbulent flow and prevent stagnant zones, improving both conveyance and agitation performance compared to symmetric uniform-blade designs
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 enables stable and efficient conveyance and agitation of developer, ensuring consistent toner density and improved image quality by preventing developer sticking and maintaining high performance over time.
Implementation Method 1
The developer is agitated and circulated by conveyance screws in a container of the developing apparatus
Implementation Method 2
The conveyance screw configured to agitate and convey developer includes: a shaft member; and a first blade and a second blade each formed helically on a circumference of the shaft member
Implementation Method 3
the first blade includes a first wide portion and a first narrow portion both located within an area in the axial direction where both of the first blade and the second blade are provided
Implementation Method 4
by which toner density is uniformed and triboelectrification of carrier and toner is performed
Implementation Method 5
triboelectrification of carrier and toner is performed
Data Source
AI summary
A conveyance screw includes a shaft member, a first blade and a second blade each formed helically on a circumference of the shaft member. The first blade includes a first wide portion and a first narrow portion both located within an area in the axial direction where both of the first blade and the second blade are provided. The first wide portion is protruded radially outward from the shaft member to a first outer diameter. The first narrow portion is formed continuously with the first wide portion in a winding direction of the first blade around the shaft member, and is protruded radially outward from the shaft member to a second outer diameter that is smaller than the first outer diameter.