Cleanerless Image-Forming Apparatus with Toner Discharge Control
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Solution Overview
Problem
In cleaner-less image forming apparatuses, the accumulation of toner on the brush member leads to image defects due to insufficient charging of the photosensitive drum, and the brush member's inability to freely vary voltage for effective cleaning results in image defects and downsizing challenges.
Innovation Solution
The image forming apparatus controls the potential difference between the brush and the photosensitive drum to manage toner accumulation by varying the surface potential of the drum, ensuring effective toner collection and prevention of image defects through controlled discharge during non-image forming periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a brush member is used to collect paper dust downstream from the transfer portion, then image defects due to paper dust are suppressed, but toner accumulates on the brush member causing charging failures
Solution Approach 1:
The patent applies periodic action by alternately switching the brush member between a paper dust collection mode (first cleaning operation with first polarity voltage) and a toner discharge mode (second cleaning operation with second polarity voltage). This periodic switching prevents toner accumulation while maintaining paper dust collection functionality, resolving the contradiction between suppressing paper dust image defects and preventing toner accumulation that causes charging failures.
Solution Approach 2:
The patent changes the polarity parameter of the voltage applied to the brush member between two states: a first polarity for collecting paper dust and a second polarity (opposite to the first) for discharging accumulated toner. By dynamically changing this electrical parameter, the system achieves both paper dust collection and toner discharge functions using the same brush member, resolving the contradiction between these two opposing requirements.
2Quantity of substance
If voltage is applied to the brush member to facilitate toner discharge, then toner accumulation is reduced, but image defects may occur during rotation cycle of the charging roller
Solution Approach 1:
The patent implements periodic action by timing the toner discharge operation to occur during non-image forming periods when the charging roller is not in its image-forming rotation cycle. The control unit switches the brush to second polarity mode only during these intervals, ensuring that toner discharge does not interfere with normal image formation, thus resolving the contradiction between reducing toner accumulation and preventing image defects.
Solution Approach 2:
The patent applies preliminary action by performing toner discharge operations in advance during non-image forming periods, before the charging roller enters its image-forming rotation cycle. This timing strategy ensures that toner is discharged from the brush member when it cannot affect image quality, preventing both accumulation and image defects.
3Ease of operation
If the brush member is made electrically conductive for voltage application, then toner discharge capability is improved, but cleaning complexity and downsizing challenges increase
Solution Approach 1:
The patent applies universality by designing the brush member to perform multiple functions: collecting paper dust during normal operation and discharging accumulated toner during non-image forming periods. By making the brush electrically conductive and controlling voltage polarity switching, a single component achieves both cleaning functions, reducing overall system complexity and supporting downsizing efforts while improving operational capability.
Solution Approach 2:
The patent changes the electrical conductivity parameter of the brush member by applying different polarities of voltage to it. During paper dust collection, a first polarity is applied, and during toner discharge, the polarity is switched to the opposite second polarity. This parameter change enables the brush to perform both functions without requiring separate components, simplifying the overall system structure.
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 approach reduces image defects and supports downsizing efforts by effectively managing toner accumulation on the brush member, enhancing cleaning performance and reducing the occurrence of image defects.
Implementation Method 1
a voltage may be applied to the brush member to make it easier for the toner to slip through
Implementation Method 2
the residual transfer toner remaining on the surface of the photosensitive drum is removed from the surface of the photosensitive drum by a developing means during the developing process
Implementation Method 3
a charging member configured to electrically charge a surface of the photosensitive member at a charging portion
Data Source
AI summary
An image forming apparatus includes a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a brush, a voltage applying portion, and a control portion controlling a surface potential of the photosensitive member at the brush contacting position. When a value of subtracting a value of the surface potential of the photosensitive member in the brush contacting position from a value of the brush voltage is defined as a contacting position potential difference, the control portion controls the surface potential of the photosensitive member in the brush contacting position so that the contacting position potential difference is changed from a first potential difference to a second potential difference in a predetermined direction which is either one of an increasing direction or a decreasing direction, and then the contacting position potential difference is changed from the second potential difference to a third potential difference in the predetermined direction.