Pre-transfer Discharge Electrode for Toner Charge Control
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Solution Overview
Problem
The existing image forming apparatus using an intermediate transfer belt faces challenges in achieving high-quality images due to variations in toner charge amount on the intermediate transfer member, leading to secondary transfer defects such as density irregularities and toner scattering, which are exacerbated by changes in system speed and environmental conditions.
Innovation Solution
A color image forming apparatus equipped with a pre-secondary-transfer electricity removal unit featuring a discharge electrode and a grid electrode, with a control system that adjusts the applied voltage based on detected current to optimize toner charge removal, ensuring consistent image quality across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If corona discharge is applied to equalize toner charge amount, then transfer charge uniformity is improved, but image defects occur due to potential increase in transfer material under low humidity or high resistance paper conditions
Solution Approach 1:
The patent applies dynamics by making the discharge electrode voltage adjustable and controllable. The voltage applied to the discharge electrode is dynamically adjusted based on detected current values to maintain optimal electricity removal without causing potential buildup on transfer material. This dynamic control allows the system to adapt to varying conditions (humidity, paper resistance) while maintaining both charge uniformity and image quality stability.
Solution Approach 2:
The patent implements feedback by using a current detecting unit to monitor the current flowing through the counter electrode and using this information to control the discharge electrode voltage. This closed-loop feedback mechanism ensures that electricity removal is optimized in real-time, preventing both insufficient charge equalization and excessive charge removal that would cause image defects.
2Reliability
If transfer voltage is suppressed to prevent image defects, then image quality is maintained, but density irregularities and toner scattering occur due to insufficient transfer electric field
Solution Approach 1:
The patent applies preliminary action by removing excess charge from the toner image on the intermediate transfer belt before the secondary transfer process. This pre-treatment ensures that the toner charge is optimized in advance, allowing the secondary transfer to proceed with appropriate voltage without causing density irregularities or toner scattering, while still preventing image defects.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the voltage applied to the discharge electrode based on detected current values. This dynamic parameter adjustment optimizes the electricity removal process to achieve the right balance: removing enough charge to prevent image defects while leaving sufficient charge to maintain proper transfer electric field strength, thereby avoiding density irregularities.
3Manufacturing precision
If electricity removal efficiency is increased, then toner charge uniformity is improved, but system complexity increases due to multiple control parameters and detection units
Solution Approach 1:
The patent applies self-service by using the current detecting unit to automatically monitor and provide feedback for controlling the discharge electrode voltage. The system self-regulates the electricity removal process based on real-time current measurements, eliminating the need for complex external control mechanisms and achieving charge uniformity through autonomous operation.
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 stabilizes image forming by effectively managing toner charge during secondary transfer, reducing defects like density irregularities and toner scattering, even under changing system speeds and environmental conditions.
Implementation Method 1
an electricity removal unit which has a discharge electrode and a grid electrode, and is provided between the primary transfer unit and the secondary transfer unit; a discharge electrode power source for applying a DC voltage with reverse polarity to the toner image on the intermediate transfer member to the discharge electrode
Implementation Method 2
a grid electrode power source for applying a DC voltage with the same polarity as the toner image on the intermediate transfer member to the grid electrode
Data Source
AI summary
A color image forming apparatus may have an image forming unit composed of a plurality of groups which have image carriers and image forming devices.