Fixing Bias Polarity Control for Dust Prevention
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Solution Overview
Problem
Conventional image forming apparatuses face issues with dust deposition and image defects due to the attraction of charged paper fillers and toner, especially when the fixing bias polarity is not correctly aligned with the filler or toner polarity, leading to incomplete cleaning and reduced apparatus lifespan.
Innovation Solution
An image forming apparatus with a conductive fixing member and a pressure member, using a toner with a binder resin and a reactant containing a polyhydric acid and a group 4 element, allowing for selective bias application to match the filler's charged polarity, reducing deposition and extending the fixing apparatus' life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixing bias with the opposite polarity to that of the toner is applied during the inter-paper period to prevent dust deposition, then the deposition of charged filler and paper powder is reduced, but the cleaning time is insufficient when inter-paper period is shortened to increase productivity
Solution Approach 1:
The fixing bias polarity is dynamically switched between positive and negative based on the charging polarity of the recording material filler. The system detects filler polarity and adjusts the fixing bias accordingly, allowing effective dust prevention during both inter-paper periods and paper passage periods without compromising productivity.
Solution Approach 2:
The invention changes the parameter of fixing bias polarity from a fixed opposite polarity to a variable polarity that matches the filler's charging polarity. This parameter adjustment ensures effective dust deposition prevention while maintaining short inter-paper periods for high productivity.
2Duration of action of stationary object
If the inter-paper period and forward/backward rotation time are minimized to extend fixing apparatus life and speed up FPOT, then the time for applying cleaning bias is reduced, but dust deposition prevention becomes insufficient
Solution Approach 1:
The fixing bias polarity is dynamically adjusted based on whether paper is passing through or during inter-paper periods. During paper passage, the bias polarity matches the filler charge to prevent dust deposition even with minimized inter-paper periods, while during inter-paper periods the opposite polarity is applied for cleaning, thus protecting the fixing apparatus without requiring extended cleaning time.
Solution Approach 2:
The system applies the appropriate fixing bias polarity in advance before dust deposition occurs. By detecting filler polarity and setting the corresponding fixing bias polarity beforehand, the system prevents dust deposition during the minimized inter-paper period, protecting the fixing apparatus surface without requiring additional cleaning time.
3Object-affected harmful factors
If a fixing bias with the same polarity as the toner is applied during paper passage to prevent dust deposition, then dust attraction is reduced, but toner image offset occurs
Solution Approach 1:
The fixing bias polarity is dynamically switched based on the operational phase: during paper passage, the polarity matches the filler charge to prevent dust deposition while maintaining proper toner fixing; during inter-paper periods, the opposite polarity is applied for cleaning. This dynamic adjustment prevents both dust deposition and toner offset, maintaining image quality.
Solution Approach 2:
The fixing bias polarity is periodically adjusted according to the paper passage cycle. During the paper passage period, the bias polarity matches the filler charge to prevent dust deposition; during the inter-paper period, the opposite polarity is applied for cleaning. This periodic action ensures dust prevention without causing toner offset, preserving image quality.
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
The solution effectively prevents the deposition of charged fillers and toner onto the fixing member, reducing image defects and extending the apparatus' lifespan by ensuring the bias polarity aligns with the filler's charge, thus maintaining image quality and apparatus longevity.
Implementation Method 1
a bias with such a polarity as to generate an electric field in the direction to hold down an unfixed toner image on a recording material is applied
Implementation Method 2
dust such as the filler charged to the opposite polarity to that of the toner or a paper powder containing the filler may be deposited on the surface of the fixing member due to the fixing bias
Data Source
AI summary
In an image forming apparatus, a fixing member has a surface layer having conductivity. A developer is a toner having a toner particle including a binder resin, a reactant of a polyhydric acid and a compound containing a group 4 element is present on a surface of the toner particle, and Tv/Fv>100 is satisfied where Tv represents a volume resistivity upon being unfixed, and Fv represents a volume resistivity after fixing. A bias applying unit can selectively apply a bias of a positive polarity and a bias of a negative polarity, and applies a bias of the same polarity as the charged polarity of a filler included in a recording material when the recording material passes through a fixing nip portion, and when the recording material does not pass through the fixing nip portion, respectively.