Image Forming Apparatus Transfer Bias Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with void images at the leading and trailing edges of transfer materials, leading to density differences and reduced transfer efficiency, particularly when handling thick or thin papers.
Innovation Solution
An image forming apparatus with a controller that applies a first bias to the leading edge area less than a second bias applied to the central area, and uses image information to control the bias based on the image formed in each area, preventing void images and density differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant voltage is applied to the transfer member for transferring toner image, then the transfer process is simple, but void images occur at the leading and trailing edges of the transfer material
Solution Approach 1:
The patent applies a time-varying transfer bias voltage that dynamically adjusts between a first voltage value for the leading edge area and a second voltage value for the central area. This dynamic voltage adjustment prevents void images at the leading and trailing edges while maintaining effective toner transfer in the central area, resolving the contradiction between simple transfer process and image quality.
Solution Approach 2:
The patent changes the voltage parameter of the transfer bias based on the position along the transfer material. By setting different voltage values (first voltage for leading edge, second voltage for central area), the patent optimizes the transfer process for different regions, preventing void images while maintaining transfer effectiveness.
2Reliability
If the transfer bias is limited to a predetermined value at leading and trailing edges, then void images are prevented, but density differences occur in the transferred image
Solution Approach 1:
The patent applies different voltage values to different areas of the transfer material: a first voltage value to the leading edge area and a second voltage value to the central area. This local differentiation prevents void images at the edges while maintaining proper toner transfer density in the central area, resolving the contradiction between image completeness and density uniformity.
3Productivity
If a high voltage is applied to ensure complete toner transfer, then transfer efficiency is high, but abnormal discharge occurs between transfer material and intermediate transfer belt
Solution Approach 1:
The patent changes the voltage parameter based on position, applying a first voltage value to the leading edge area and a second voltage value to the central area. This parameter differentiation ensures complete toner transfer in the central area while preventing abnormal discharge at the leading edge, resolving the contradiction between transfer efficiency and harmful discharge.
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 effectively prevents void images at the leading and trailing edges while maintaining consistent image density, enhancing transfer efficiency and reducing the occurrence of density differences.
Implementation Method 1
a transfer member which transfers a toner image formed on an image bearing member to a transfer material
Implementation Method 2
a transfer bias application unit which applies bias to the transfer member
Data Source
AI summary
An image forming apparatus includes a transfer member which transfers a toner image formed on an image bearing member to a transfer material; a transfer bias application unit which applies bias to the transfer member; a controller which executes a mode for making a first bias applied to a first predetermined area arranged at a leading edge of a transfer material with respect to a conveying direction of the transfer material to be less than a second bias applied to a second predetermined area arranged in a central area of the transfer material; and an obtaining portion which obtains image information of an image formed in each area obtained by dividing an area corresponding to the leading edge area into plural pieces in the width direction, wherein the controller controls the first bias based on image information obtained by the obtaining portion at the time of the mode.