Transfer Bias Control for Toner Pattern Removal
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Solution Overview
Problem
Existing image forming apparatuses face challenges in thoroughly removing toner patterns from the intermediate transfer belt and photoconductive drum surfaces, leading to potential transfer issues and image quality problems, especially when using recording media with coarse surfaces.
Innovation Solution
The apparatus employs a transfer bias with an alternating current component superimposed on a direct current component to transfer toner images and a charge eliminating bias to facilitate the removal of toner patterns, combined with a mechanical cleaning device to ensure complete toner removal from the image bearing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a direct current voltage bias is supplied to transfer toner images, then toner transfer efficiency is improved, but toner patterns remain on the intermediate transfer belt causing image quality deterioration
Solution Approach 1:
The patent applies periodic action by switching between two bias modes: a first bias (direct current voltage) is applied during normal toner transfer to ensure efficient transfer, while a second bias (alternating current voltage) is periodically applied to eliminate residual toner patterns on the intermediate transfer belt. This periodic switching prevents toner accumulation and maintains consistent image quality across multiple recording sheets.
2Device complexity
If toner patterns are not removed from the intermediate transfer belt, then cleaning device complexity is reduced, but subsequent recording media receive defective toner transfer
Solution Approach 1:
The patent replaces complex mechanical cleaning systems with an electrical field-based solution. By applying an alternating current voltage bias to the intermediate transfer belt, residual toner patterns are electrostatically eliminated without requiring additional mechanical cleaning devices, thereby maintaining reliability while avoiding increased device complexity.
3Manufacturing precision
If a mechanical cleaning device is added to remove toner patterns, then image quality is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent eliminates the need for mechanical cleaning devices by using electrical field control. The alternating current voltage bias creates an electrostatic field that removes residual toner patterns from the intermediate transfer belt, achieving high image quality without adding mechanical cleaning components that would increase device complexity and maintenance requirements.
4Speed
If the intermediate transfer belt is not cleaned between recording sheets, then processing speed is maintained, but toner patterns transfer to subsequent recording media
Solution Approach 1:
The patent implements periodic action by applying the alternating current voltage bias at specific intervals between recording sheets. This periodic electrical cleaning maintains processing speed by not requiring physical cleaning operations, while simultaneously preventing toner pattern transfer to subsequent recording media, thus maintaining both speed and 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
This approach effectively prevents toner pattern transfer to subsequent recording media, maintains image quality by ensuring uniform toner density, and enhances the cleaning efficiency of toner from the intermediate transfer belt and photoconductive drum surfaces.
Implementation Method 1
The transfer bias applicator supplies a transfer bias in which an alternating current component and a direct current component are superimposed to transfer the toner image onto a recording medium in the transfer nip
Implementation Method 2
The transfer bias applicator supplies a charge eliminating bias to remove charge from toner in the toner pattern when the toner pattern passes through the transfer nip
Data Source
AI summary
An image forming apparatus includes an image bearing member, an image forming unit for forming a toner image and a toner pattern comprising toner not to be transferred onto a recording medium for adjustment of a density of toner on a surface of the image bearing member, a nip forming member contacting the surface of the image bearing member to form a transfer nip therebetween, a transfer bias applicator for applying a transfer bias in which an alternating current component and a direct current component are superimposed to transfer the toner image onto the recording medium in the transfer nip, a first cleaning device to mechanically remove toner remaining on the image bearing member after passing through the transfer nip. The transfer bias applicator applies a charge eliminating bias to remove charge from toner in the toner pattern when the toner pattern passes through the transfer nip.