Magnetic Roller Toner Collection via Reverse Rotation
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Solution Overview
Problem
In image forming apparatuses using the two-component development method, scattered toner often deposits on the restricting member and subsequently transfers to the photosensitive drum, leading to degraded image quality.
Innovation Solution
An image forming apparatus with a magnetic roller, developing roller, restricting member, first and second voltage application sections, and a controller, which executes a toner collection mode by reversing the rotation direction of the magnetic roller and setting biases to prevent toner transfer during image formation, allowing for the collection of scattered toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the restricting member restricts the layer thickness of the developer on the magnetic roller, then the layer thickness becomes uniform, but toner scatters around the restricting member and deposits on it, leading to degraded image quality
Solution Approach 1:
A collecting member is introduced as an intermediary component positioned downstream of the restricting member. This collecting member captures the scattered toner particles before they can deposit on the restricting member or photosensitive drum, thereby resolving the contradiction between achieving uniform layer thickness and preventing toner scattering harm
Solution Approach 2:
The scattered toner, which was previously a harmful factor causing image degradation, is converted into a collectible resource. The collecting member captures these scattered toner particles and returns them to the developer container, transforming the harmful scattering effect into a beneficial toner recovery mechanism
2Productivity
If toner is fed from the developing roller to the photosensitive drum, then image development occurs, but scattered toner falls onto the restricting member and transfers to the photosensitive drum, degrading image quality
Solution Approach 1:
The collecting member serves as an intermediary between the restricting member and the photosensitive drum, intercepting scattered toner particles in the air path and preventing their harmful deposition on the photosensitive drum while maintaining normal image development processes
3Object-generated harmful factors
If the photosensitive drum rotation is stopped and the developing roller rotates in reverse to scrape off toner deposit, then toner removal is achieved, but image formation is interrupted
Solution Approach 1:
The collecting member is positioned to proactively capture scattered toner particles before they can accumulate into significant deposits on the restricting member or photosensitive drum. This preliminary action prevents the need for interrupting image formation to remove deposits, maintaining continuous productivity
Solution Approach 2:
The collecting member continuously and automatically captures and returns scattered toner to the developer container without requiring manual intervention or interruption of the image formation process, enabling the system to self-maintain optimal 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
Prevents toner deposition on the photosensitive drum, thereby maintaining image quality and extending the lifespan of the apparatus by effectively managing toner distribution and collection.
Implementation Method 1
The magnetic roller, by action of a magnet included in it, carries two-component developer containing toner and magnetic carrier in the form of a magnetic brush
Implementation Method 2
The first voltage application section applies a first bias to the magnetic roller. The second voltage application section applies a second bias to the magnetic roller
Implementation Method 3
The restricting member is arranged under the developing roller at a predetermined interval from the magnetic roller, and restricts the layer thickness of the developer on the surface of the magnetic roller
Data Source
AI summary
An image forming apparatus has a first voltage application section for applying a first bias to a magnetic roller, a second voltage application section for applying a second bias to a developing roller, and a controller for controlling the voltages of the first and second voltage application sections and the driving/rotating of the magnetic roller and the developing roller. When no image formation is taking place, the controller can execute a toner collection mode in which, with the first and second biases set at the same potential and the second bias set lower than the voltage applied to an image carrying member, the magnetic roller is rotated in the direction reverse to that in which it is rotated during image formation.