Duplex Image Forming Apparatus Voltage Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, during duplex printing, toner can adhere to the conveyance guide due to incomplete fixation on the recording material, leading to soiling as the number of sheets increases, especially when a voltage of opposite polarity is applied to the guidance member to prevent transfer current leakage.
Innovation Solution
The image forming apparatus controls a potential difference between the photoconductor and the guidance member, reducing the voltage applied to the guidance member during duplex printing on the second surface to prevent toner adhesion, while maintaining an opposite polarity voltage for the transfer member to ensure efficient transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage of opposite polarity is applied to the conveyance guide to prevent transfer current leakage, then transfer efficiency is improved, but toner adheres to the conveyance guide causing soiling
Solution Approach 1:
The patent applies a voltage to the conveyance guide during single-sided printing to prevent transfer current leakage, but stops or reduces the voltage during duplex printing to prevent toner adhesion. This dynamic adjustment of the voltage based on the printing mode resolves the contradiction between maintaining transfer efficiency and preventing soiling.
Solution Approach 2:
The patent changes the voltage parameter of the conveyance guide based on the printing mode. During single-sided printing, a voltage of opposite polarity is applied to prevent transfer current leakage. During duplex printing, the voltage is reduced or stopped to prevent toner adhesion. This parameter change resolves the technical contradiction.
2Reliability
If voltage is applied to the guidance member during duplex printing, then transfer current leakage is prevented, but toner deposits in the guidance member increasing with sheet count
Solution Approach 1:
The patent applies voltage to the conveyance guide periodically based on the printing mode. During single-sided printing, voltage is applied to control transfer current. During duplex printing, voltage is stopped or reduced to prevent toner deposition. This periodic action based on printing mode resolves the contradiction.
Solution Approach 2:
The patent dynamically adjusts the voltage application to the conveyance guide based on whether single-sided or duplex printing is being performed. This dynamic control prevents toner deposition while maintaining transfer current control when needed.
3Productivity
If opposite polarity voltage is maintained on conveyance guide for all printing modes, then transfer efficiency is maintained, but toner adhesion occurs on second surface printing
Solution Approach 1:
The patent dynamically controls the voltage application to the conveyance guide based on the printing mode. During single-sided printing, opposite polarity voltage is applied to maintain transfer efficiency. During duplex printing, the voltage is stopped or reduced to prevent toner adhesion on the second surface.
Solution Approach 2:
The patent changes the voltage parameter of the conveyance guide based on printing mode to resolve the contradiction between maintaining transfer efficiency and preventing toner adhesion during duplex printing.
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 effectively prevents toner deposition on the guidance member, reducing soiling and maintaining transfer efficiency by adjusting the potential difference during duplex printing, thereby minimizing toner adhesion and leakage.
Implementation Method 1
a photoconductor (1) on which an electrostatic latent image is formed; a charging member (2) configured to charge the photoconductor
Implementation Method 2
a developing member (4) configured to develop the electrostatic latent image formed on the photoconductor with toner charged to predetermined polarity
Implementation Method 3
a transfer member (5) configured to form a transfer portion together with the photoconductor and to transfer a toner image from the photoconductor to a recording material; a transfer power source (5a) configured to apply a voltage of polarity opposite to the predetermined polarity to the transfer member
Implementation Method 4
an auxiliary power source (50a) configured to apply a voltage of the opposite polarity to the guidance member (50); A leakage of a transfer current from the transfer member through the recording material can be prevented by applying a voltage of polarity opposite to charging polarity of toner to the conveyance guide
Implementation Method 5
a fixing unit (12) configured to fix the toner image transferred from the photoconductor to the recording material
Data Source
AI summary
In a configuration in which a voltage of polarity opposite to charging polarity of toner is applied to a conveyance guide, controlling deposition of toner on the conveyance guide has been difficult. When performing duplex image formation, a potential difference between a surface potential of a photoconductive drum charged by a charging roller and a potential of the conveyance guide is smaller during printing on the second surface than during printing on the first surface.