Developing Device with Guided Used-Developer Separation
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Solution Overview
Problem
The existing developing device with two developing rollers is prone to image defects such as density unevenness due to the mixing of used developer with normal developer, exacerbated by high-speed operation and temperature rise, leading to co-rotation phenomena.
Innovation Solution
The developing device incorporates a specific arrangement of rotatable members and magnets with defined distances between them to control developer flow, ensuring that used developer is properly guided and collected, preventing mixing with fresh developer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the developer is delivered from the second developing roller to the peeling roller by air flow, then the developer can be transported efficiently, but a part of the used developer is carried along with the air flow and dropped on the first developing roller, causing toner concentration non-uniformity
Solution Approach 1:
The invention extracts and removes the harmful air flow path that causes used developer to be carried to the first developing roller. By introducing a partition wall and guiding portion, the air flow is redirected to exclude the first developing roller from the developer delivery path between the second developing roller and peeling roller, thus eliminating the co-rotation phenomenon while maintaining delivery efficiency
Solution Approach 2:
The guiding portion acts as an intermediary structure that controls and directs the air flow and developer movement. It serves as a mediator between the second developing roller/peeling roller system and the first developing roller, preventing direct interaction that causes contamination while allowing the air flow to continue functioning for developer transport
2Productivity
If the image forming apparatus is operated at high speed, then productivity increases, but temperature rise in the developing device exacerbates the co-rotation phenomenon and image defects
Solution Approach 1:
The invention applies preliminary anti-action by preventing the co-rotation phenomenon before it can occur. The partition wall and guiding portion are configured in advance to block the path of used developer before temperature rise and high-speed operation can exacerbate the air flow effects, thus maintaining image quality stability even under high-speed operating conditions
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 arrangement suppresses the occurrence of image defects by maintaining consistent developer toner levels and preventing uneven developer distribution, thus ensuring high-quality image output.
Implementation Method 1
a first magnet fixedly provided inside the first rotatable member; a second rotatable member which is provided opposed to the first rotatable member, to which the developer is delivered from the first rotatable member by a magnetic field generated by the first magnet
Implementation Method 2
a second magnet fixedly provided inside the second rotatable member; a third rotatable member which is provided opposed to the second rotatable member, to which the developer is delivered from the second rotatable member by a magnetic field generated by the second magnet
Implementation Method 3
the developer, peeled off from the third rotatable member by a repelling magnetic field generated by the third magnet
Data Source
AI summary
A developing device includes a first rotatable member to which developer is delivered, a second rotatable member provided opposed to the first rotatable member, to which the developer is delivered from the first rotatable member by a magnetic field generated by a first magnet, to carry and feed the developer, and a third rotatable member provided opposed to the second rotatable member, to which the developer is delivered from the second rotatable member. A guiding portion is provided opposed to the second and third rotatable members to guide the developer peeled off from the third rotatable member by a repelling magnetic field generated by a third magnet. Where a shortest distance between the second rotatable member and the guiding portion is B [μm], and a shortest distance between the third rotatable member and the guiding portion is C [μm], the following relationship is satisfied: B+100 μm≤<C.