Secondary Transfer Bias Waveform for Embossed Media
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in transferring toner onto recording media with coarse surfaces, such as leather-like or embossed papers, leading to gaps in the output image due to electric discharge and excessive toner charge, especially in DC-AC superimposed transfer modes.
Innovation Solution
The image forming apparatus employs a secondary transfer bias with a waveform that alternates polarity between a transfer polarity and an opposite polarity, using a smaller absolute DC component in the superimposed transfer mode compared to the DC transfer mode, and adjusts the AC voltage to prevent electric discharge and enhance toner transfer to recessed portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the DC bias strength is increased to enhance toner transfer to recessed portions, then transferability to recessed portions is improved, but electric discharge occurs causing image degradation
Solution Approach 1:
The patent applies periodic action by superimposing an AC voltage with alternating polarity onto the DC transfer bias. The AC component periodically reverses polarity, which prevents electric discharge by avoiding sustained high-voltage conditions while maintaining effective toner transfer to recessed portions through the alternating electric field.
Solution Approach 2:
The patent changes the parameter of transfer bias by transitioning from a pure DC voltage to a superimposed DC-AC voltage waveform. This parameter change allows the system to achieve both strong transfer to recessed portions and prevention of electric discharge by optimizing the voltage waveform characteristics.
2Manufacturing precision
If the AC voltage peak-to-peak value is increased to enhance transfer to recessed portions, then transferability is improved, but electric discharge occurs causing white dot images
Solution Approach 1:
The patent uses periodic action through AC voltage superposition to achieve effective toner transfer to recessed portions without generating white dot images. The alternating polarity of the AC component prevents sustained high-voltage conditions that would cause electric discharge and white dot defects.
Solution Approach 2:
The patent converts the potentially harmful effect of high AC voltage (which causes electric discharge) into a beneficial alternating electric field that effectively transfers toner to recessed portions. By carefully controlling the AC waveform, the system achieves good transfer without the harmful discharge effects.
3Stability of the object's composition
If the polarity of AC voltage is increased to maintain constant polarity opposite to transfer direction, then transfer stability is improved, but voltage exceeds threshold causing electric discharge
Solution Approach 1:
The patent applies periodic action by using AC voltage with alternating polarity that maintains stable transfer characteristics. The alternating polarity ensures that the AC component remains opposite to the transfer direction at critical moments, maintaining transfer stability while preventing voltage threshold exceedance through the periodic nature of the waveform.
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 solution prevents image degradation by reducing toner charge and enhancing transferability to both recessed and projecting portions, ensuring consistent and high-quality image formation on various types of recording media.
Implementation Method 1
a secondary transfer member supplied with a secondary transfer bias to transfer the toner image from the intermediate transfer member onto a recording medium
Implementation Method 2
a superimposed bias in which an alternating current (AC) voltage is superimposed on a DC voltage... prevents image degradation such as little or no settling of toner in the recessed portions and discharge images
Data Source
AI summary
A novel image forming apparatus includes a photoreceptor to bear an electrostatic latent image on a surface thereof, a developing device to develop the electrostatic latent image into a toner image, an intermediate transfer member onto which the electrostatic latent image is transferred, a primary transfer member to apply a primary transfer bias to the intermediate transfer member to transfer the toner image thereto, a secondary transfer member supplied with a secondary transfer bias to transfer the toner image from the intermediate transfer member onto a recording medium, and a transfer bias power source to selectively apply to the secondary transfer member one of a secondary transfer bias consisting of a direct current (DC) voltage in a DC transfer mode and a secondary transfer bias consisting of a superimposed bias in which an alternating voltage is superimposed on a DC voltage.