Developing Device Screw Vane Design for Developer Level Control
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Solution Overview
Problem
Conventional developing devices with shutter systems face challenges in maintaining a constant developer level due to pressure imbalances caused by increased rotation speed, leading to excessive developer discharge and complications such as convection and increased device size and cost.
Innovation Solution
A developing device with a first and second circulation tank, where the first screw has vanes in specific portions to convey and balance developer flow, and a second screw in the second tank for circulation, maintaining appropriate developer levels without vanes near the opening to prevent excessive discharge, and a separate outlet in the first tank for controlled developer discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation speed of the developer conveying screw is increased to increase printing speed, then productivity is improved, but the pressure balance is lost causing excessive developer discharge
Solution Approach 1:
The developer tank is divided into two separate circulation tanks (first circulation tank and second circulation tank) by a partition wall. Each tank has its own conveying screw with independently controllable vanes, allowing separate control of developer circulation in each tank. This segmentation enables precise control of developer discharge while maintaining constant developer levels even at high rotation speeds.
Solution Approach 2:
The conveying screw is designed with non-uniform vane distribution: the first screw has vanes only in specific portions (first and third portions) but no vanes in the second portion near the opening. This local variation in vane presence creates different pressure characteristics in different regions of the tank, allowing the system to maintain pressure balance and prevent excessive discharge while operating at high speeds.
2Quantity of substance
If a shutter system is added to control developer discharge, then developer level control is improved, but device complexity and size increase
Solution Approach 1:
The invention removes the shutter system entirely from the developer discharge control mechanism. Instead of using a shutter to mechanically control discharge, the system relies on the inherent pressure balance created by the dual-tank configuration and the specifically designed vane distribution on the conveying screws. This extraction of the shutter component significantly simplifies the system structure while maintaining effective developer level control.
Solution Approach 2:
The system uses the natural pressure balance created by the dual circulation tanks and strategically placed vanes to automatically regulate developer discharge. The first vane and second vane on the conveying screw work together to create pressure equilibrium that self-regulates the developer flow, eliminating the need for external control mechanisms like shutters.
3Quantity of substance
If a shutter system is added to adjust discharged developer amount, then developer level control is improved, but the risk of outlet closure and convection increases
Solution Approach 1:
The shutter component that causes outlet closure and convection problems is completely removed from the system. Developer discharge is controlled through the pressure balance mechanism of the dual circulation tanks and the vane configuration on the conveying screw, eliminating the mechanical shutter that would otherwise block the outlet or cause unwanted convection currents.
Solution Approach 2:
The partition wall and the strategically positioned vanes act as intermediaries to control developer flow and pressure distribution. Instead of using a shutter that directly blocks the outlet, the system uses the partition wall to separate circulation paths and the vanes to mediate pressure balance, thereby controlling discharge without creating outlet closure or convection issues.
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 device effectively maintains an appropriate developer level in the tank across varying rotation speeds, preventing excessive discharge and convection issues, while simplifying the system and reducing the risk of outlet closure, thus ensuring consistent image quality without the complexity and cost of shutter systems.
Implementation Method 1
the first screw has a first vane in a first portion upstream from the first opening with respect to a conveying direction of the first screw, the first vane exerting a force in the conveying direction on the developer; the first screw has a second vane in a third portion adjacently downstream from the second portion with respect to the conveying direction, the second vane exerting a force in a direction opposite to the conveying direction on the developer
Implementation Method 2
a second screw provided in the second circulation tank so as to convey the developer
Data Source
AI summary
A developing device has a first circulation tank and a second circulation tank. A developer is conveyed from the first circulation tank to the second circulation tank through a first opening, while the developer is partly discharged through an outlet. The developer conveyed to the second circulation tank is conveyed back in the first circulation tank via a second opening. A first screw provided in the first circulation tank has a first vane, which exerts a force in a conveying direction of the first circulation path, in a first portion upstream from the first opening with respect to the conveying direction. The first screw has no vanes in a second portion near the first opening. The first screw has a second vane, which exerts a force in a direction opposite to the conveying direction, in a third portion adjacently downstream from the second portion. The outlet is located at a point of the first circulation tank, downstream from the second vane. A portion of the first circulation tank downstream from the second vane is not connected to the second circulation tank in a direction perpendicular to the conveying direction.