Tandem Image Forming Apparatus Double-Side Discharge Control
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Solution Overview
Problem
In tandem type image forming apparatuses, the increased surface potential of sheets during double-side printing leads to reduced transfer efficiency of toner images due to increased electrical resistance, causing discharge between the transfer roller and the sheet.
Innovation Solution
The image forming apparatus adjusts the transfer bias setup, with the transfer bias on the most downstream side being greater than others, and adjusts the developing bias to a lower value for the second surface in double-side printing mode to prevent discharge and maintain efficient toner transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transfer bias is increased to compensate for sheet potential increase, then transfer efficiency is improved, but discharge between transfer roller and sheet occurs
Solution Approach 1:
The patent applies preliminary action by reducing the developing bias before the toner transfer process. By lowering the developing bias in advance, the toner charge quantity is reduced, which prevents excessive sheet potential accumulation and subsequent discharge during the transfer process, while still maintaining adequate transfer efficiency
Solution Approach 2:
The patent changes the developing bias parameter to a lower value specifically for double-side printing mode. This parameter change reduces the toner charge quantity and sheet potential accumulation, thereby preventing discharge while maintaining transfer efficiency through optimized bias settings
2Object-affected harmful factors
If the developing bias is reduced to prevent discharge, then discharge is prevented, but toner transfer efficiency may be reduced
Solution Approach 1:
The patent optimizes the developing bias parameter by setting it to a lower value specifically for double-side printing mode. This parameter optimization balances the contradiction by reducing bias enough to prevent discharge while maintaining sufficient toner transfer efficiency through careful calibration
Solution Approach 2:
The patent implements dynamic bias adjustment where the developing bias is differentiated based on printing mode. Single-side printing uses a higher bias for optimal transfer, while double-side printing uses a lower bias to prevent discharge, allowing the system to adapt to different operational conditions
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 discharge and enhances the transfer efficiency of toner images from photosensitive drums to sheets, ensuring high-quality color images in both single-side and double-side printing modes.
Implementation Method 1
a developing bias for forming potential difference between the developing roller and the photosensitive drum is applied to the developing roller... a toner is fed from the developing roller to the electrostatic latent image due to the potential difference between the photosensitive drum and the developing roller
Implementation Method 2
a transfer bias for forming potential difference between the transfer roller and the photosensitive drum is applied to the transfer roller... the toner image is transferred from the photosensitive drum to the sheet due to the potential difference between the photosensitive drum and the sheet
Implementation Method 3
The color toner images overlapped on the sheet are fixed to the sheet as a color image by heating and pressurization
Data Source
AI summary
An image forming apparatus includes a transfer bias set up section and a developing bias set up section. The transfer bias set up section sets a transfer bias applied to each transfer member so that the transfer bias applied to a transfer member corresponding to a photosensitive member on the most downstream side is greater than a transfer bias applied to a transfer member other than this transfer member. The developing bias set up section sets a developing bias applied to each developing member to a first developing bias in a single-side printing mode, and sets up the developing bias applied to each developing member in formation of an image on a first surface and in formation of another image on a second surface to a second developing bias lower than the first developing bias when the image formed on the second surface is a color image.