Developing Device Toner Packing Prevention
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Solution Overview
Problem
Existing developing devices in electrophotographic image forming apparatuses suffer from toner packing issues beneath the nip portion between the developing and feed rollers, leading to gear rotation difficulties and potential image quality deterioration or gear breaks, while also being large and complex in structure due to the need for toner agitating/conveying members.
Innovation Solution
A developing device with a housing containing nonmagnetic toner, a developing roller, a feed roller in parallel pressure contact, and a feed stabilizing member forming a second nip portion to restrict toner feed, along with a toner circulation path that uses the pressure of accumulating toner to prevent packing by circulating it back to a second region, eliminating the need for additional agitating/conveying members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If toner agitating/conveying members are provided below the nip portion to prevent toner packing, then toner packing is prevented, but the device becomes large-sized and complex in structure
Solution Approach 1:
The invention extracts and eliminates the toner agitating/conveying members from the device structure. Instead of adding complex mechanical components to agitate and convey toner, the patent uses the natural gravity-driven flow of toner combined with a specially designed housing geometry that guides toner circulation, thereby preventing toner packing without requiring additional agitating mechanisms.
Solution Approach 2:
The toner circulation system operates autonomously using the weight and natural flow of toner itself. The housing configuration creates a self-circulating toner flow path where toner naturally moves from the nip portion downward and circulates back, eliminating the need for external drive sources or mechanical agitating components.
2Reliability
If a wide space is provided below the nip portion for toner to drop, then toner packing is prevented, but the device size increases
Solution Approach 1:
The invention optimizes the spatial configuration by utilizing the vertical dimension and housing wall surfaces to guide toner circulation. Instead of providing a wide horizontal space, the patent designs the housing to create efficient vertical and lateral flow paths along the inner walls, allowing compact toner circulation without increasing overall device volume.
Solution Approach 2:
The housing is designed with specific local geometric features including inclined surfaces and flow-guiding configurations in the toner circulation path. These localized structural optimizations enable efficient toner flow and circulation in a compact space, preventing toner packing without requiring a large overall device volume.
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
Prevents toner packing, thereby avoiding image quality deterioration and gear issues, while allowing for a compact and simplified device design by utilizing the toner circulation path to manage toner accumulation effectively.
Implementation Method 1
a feed roller which is set in the housing parallel to the developing roller in pressure contact with the developing roller
Implementation Method 2
a toner circulation path for pushing back toner from the first region through below the feed stabilizing member to a second region corresponding to a place upper than the feed stabilizing member on the one side of the second nip portion opposite to the first region side with an aid of pressure of toner that tends to accumulate in the first region
Data Source
AI summary
A developing device including a housing, toner a developing roller, and a feed roller in pressure contact with the developing roller so as to form a nip portion and which feeds toner to the developing roller. The developing device including a feed stabilizing member contacting a lower portion of the feed roller so as to form a second nip portion and restricting toner feed quantity. The feed stabilizing member extending from a generally triangular-shaped first region below the first nip portion up to one side of the nip portion opposite to the first region side. The developing device further including a toner circulation path for pushing back toner from the first region through below the feed stabilizing member to a second region on the one side opposite to the first region side with an aid of pressure of toner that tends to accumulate in the first region.