Charging Roller Charge Attenuation for Stripe-Free Image Forming
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Solution Overview
Problem
The accumulation of toner and external additives on the charging roller in electrophotographic image forming apparatuses leads to improper charging, resulting in density non-uniformity and charging lateral stripe images due to triboelectric charges between the cleaning and charging rollers, which are not effectively addressed by existing solutions.
Innovation Solution
The image forming apparatus is designed with a time constant τ=½×fp, where fp is the frequency of impedance measurement maximum, ensuring A/τ≥60, to attenuate triboelectric charges and prevent intermittent electric discharges, thereby suppressing charging lateral stripe images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cleaning roller contacts the charging roller to remove deposited matter, then the charging roller is cleaned and improper charging is prevented, but triboelectric charge occurs between the rollers causing charging lateral stripe images
Solution Approach 1:
A charge neutralizing member is introduced as an intermediary between the cleaning roller and the charging roller. This mediator transfers charge from the charging roller to the charge neutralizing member, preventing triboelectric charge accumulation at the cleaning roller contact point and eliminating charging lateral stripe images while maintaining cleaning effectiveness.
2Reliability
If the cleaning roller continuously contacts the charging roller, then deposited matter is removed, but the triboelectric charge accumulates and causes intermittent electric discharge
Solution Approach 1:
The charge neutralizing member acts as a charge transfer intermediary, receiving excess charge from the charging roller through controlled contact. This prevents charge accumulation that would otherwise lead to intermittent electric discharge, ensuring consistent charging performance during continuous operation.
3Ease of operation
If the charging roller surface potential is reduced by triboelectric charge, then cleaning effectiveness is improved, but electric discharge from the charging roller becomes unstable
Solution Approach 1:
The charge neutralizing member provides controlled charge transfer that maintains charging roller surface potential within an optimal range. By preventing excessive triboelectric charge accumulation, it ensures stable electric discharge while preserving sufficient cleaning effectiveness through the cleaning roller contact.
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 effectively suppresses charging lateral stripe images by ensuring the triboelectric charge is quickly attenuated, maintaining consistent charging and reducing image defects.
Implementation Method 1
Both of the cleaning roller and the charging roller are formed of resin at surfaces (outer peripheral surfaces, outer surfaces) thereof in many cases, and triboelectric charge generated by friction therebetween becomes a problem in some cases.
Implementation Method 2
a time constant τ of the charging member is a value represented by τ=1⁄2×fp [sec], wherein fp is a frequency at which an absolute value of an imaginary part obtained by impedance measurement of the charging member shows a maximum value
Data Source
AI summary
When a time from when a point of the surface of the charging member contacts the cleaning member until the point subsequently contacts the cleaning member again by a rotation of the charging member is defined as a rotation time A [sec], and a time constant τ of the charging member is a value represented by τ=½πfp [sec], wherein fp is a frequency at which an absolute value of an imaginary part obtained by impedance measurement of the charging member shows a maximum value, and the time constant τ is defined as an index indicating that an electric charge of the surface of the charging member is attenuated, the rotation time A and the time constant τ satisfy the following relationship: A/τ≥60, wherein the time constant τ is 1.0×10−5 [sec] or more and 1.2×10−3 [sec] or less.