Image Forming Apparatus Transfer Bias Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In image forming apparatuses using the electrophotographic method, excessive lowering of the surface potential of the photosensitive member can lead to toner expulsion and degradation of image quality due to increased transfer bias, causing residual toner to adhere back onto the image bearing member.
Innovation Solution
An image forming apparatus with a controller that selectively applies different transfer biases and charging biases to manage the surface potential of the image bearing member, utilizing a cleaning member to remove residual developer and prevent toner adhesion, by adjusting transfer currents and charging biases based on humidity or electric resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transfer bias is increased to maintain electric field between photosensitive member and transfer roller, then transfer efficiency is prevented from degrading, but surface potential of photosensitive member is excessively lowered causing toner expulsion
Solution Approach 1:
The patent applies multiple transfer biases (first transfer bias and second transfer bias) and multiple charging biases (first charging bias and second charging bias) to dynamically adjust the electric field parameters. By changing these parameters based on operating conditions, the system maintains transfer efficiency while preventing excessive surface potential lowering that would cause toner expulsion.
Solution Approach 2:
The system dynamically switches between different transfer biases and charging biases during operation. The controller selectively applies the first or second transfer bias and first or second charging bias based on real-time conditions, making the system adaptive rather than static, thereby resolving the contradiction between maintaining electric field strength and preventing surface potential excessive lowering.
2Productivity
If transfer bias is increased to maintain electric field, then transfer efficiency is maintained, but residual toner adheres back onto photosensitive member degrading image quality
Solution Approach 1:
By implementing multiple transfer biases and charging biases, the system optimizes the electric field parameters to maintain efficient toner transfer while preventing the conditions that cause residual toner to adhere back onto the photosensitive member, thereby preserving image quality.
Solution Approach 2:
The controller monitors operating conditions and selectively applies appropriate transfer biases and charging biases based on feedback from the system state. This feedback mechanism ensures that transfer efficiency is maintained while preventing image quality degradation from residual toner adhesion.
3Reliability
If multiple transfer biases and charging biases are applied to manage surface potential, then toner expulsion is prevented, but device complexity increases
Solution Approach 1:
The system uses a controller that dynamically selects between predefined transfer biases and charging biases based on operating conditions. Rather than requiring complex real-time calculations, the system switches between discrete, pre-determined parameter sets, which simplifies the control architecture while maintaining reliable surface potential control.
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
Prevents excessive surface potential lowering and ensures reliable cleaning of the image bearing member, maintaining image quality by effectively transferring toner images while preventing residual toner from adhering back onto the photosensitive drums.
Implementation Method 1
The charging member is configured to apply an electric charge to the surface of the image bearing member
Implementation Method 2
The transfer member is configured to transfer the developer image carried on the surface of the image bearing member to a transfer medium
Implementation Method 3
The cleaning member is configured to remove residual developer that remains on the surface of the image bearing member
Data Source
AI summary
An image forming apparatus includes: an image forming unit; and a controller. The image forming unit includes: an image bearing member; a charging member; a transfer member; and a cleaning member. The controller selectively applies first and second transfer biases to the transfer member. A first transfer current flows between the image bearing member and the transfer member upon application of the first transfer bias. A second transfer current flows therebetween upon application of the second transfer bias. The controller selectively applies first and second charging biases to the charging member. The image bearing member has a first surface potential upon application of the first charging bias, and a second surface potential upon application of the second charging bias. The controller applies the first charging bias when applying the first transfer bias, and applies the second charging bias when applying the second transfer bias.