Developing Device Airflow Management for Developer Loss
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Solution Overview
Problem
In electrophotographic developing devices, airflow generated by the rotation of the developer carrying member can lead to the discharge of developer through the discharge opening, resulting in a reduction of the developer amount in the developing container, which affects image quality and can cause abnormal images due to insufficient developer supply.
Innovation Solution
A developing device design that includes a rotatable developing member, a developing container with partitioned chambers, and specific blade configurations on feeding screws to manage airflow and developer circulation, with a third communication opening positioned downstream of the discharge opening to direct airflow and reduce developer discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the developer carrying member is rotated at high speed, then the developer circulation and image formation speed are improved, but airflow is generated that causes developer to be discharged through the discharge opening
Solution Approach 1:
The patent utilizes the airflow generated by high-speed rotation of the developer carrying member and directs it through a specifically designed airflow passage to promote developer circulation between chambers. The harmful airflow that causes developer discharge is converted into a beneficial force that enhances developer mixing and circulation, while the discharge opening is positioned to minimize unwanted loss.
2Reliability
If the discharge opening is provided in the first chamber, then the deteriorated developer can be discharged, but airflow causes developer to be discharged in mixture with airflow reducing developer amount
Solution Approach 1:
The patent divides the developing container into two separate chambers (first chamber for developer supply and second chamber for developer circulation) with controlled communication between them. The discharge opening is specifically positioned in the first chamber downstream of the communication portion, allowing deteriorated developer to be discharged while maintaining separation between the supply and circulation functions. This segmentation prevents airflow from causing excessive developer discharge while still enabling quality maintenance.
3Productivity
If the communication portion establishes communication between first and second chambers, then developer circulation is improved, but airflow can pass through causing developer discharge
Solution Approach 1:
The patent implements different functional zones within the chambers by strategically positioning the communication portion and discharge opening. The communication portion allows developer circulation while the discharge opening is positioned downstream to handle only deteriorated developer. The local structural characteristics (communication portion for circulation, discharge opening for quality control) enable differentiated functions that prevent harmful airflow effects while maintaining circulation efficiency.
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
This design effectively reduces the amount of developer discharged due to airflow, maintaining a consistent developer supply and preventing abnormal images, even at high process speeds, ensuring stable image formation.
Implementation Method 1
by rotating the first and second feeding screws, the developer is fed and circulated between the first and second chambers while being stirred
Implementation Method 2
by rotation of the developer carrying member, airflow is drawn from an outside to an inside of the developing device
Implementation Method 3
When such airflow is generated, the developer in the developing container is also discharged through the discharge opening in mixture with this airflow
Data Source
AI summary
A developing device includes a rotatable developing member, a developing container, a first communication opening, a second communication opening, a first feeding screw including a first rotation shaft, first and second blade portions, a second feeding screw including a second rotation shaft, third and fourth blade portions, a developer discharge opening provided upstream of an upstream end of the second communication opening in a first direction, and a third communication opening provided upstream of the upstream end of the second communication opening in the first direction. In a second direction opposite to the first direction, the third communication opening overlaps with the second blade portion. In the first direction, the third communication opening overlaps with the fourth blade portion. In the first direction, a downstream end of the third communication opening is positioned downstream of a downstream end of the developer discharge opening.