Transfer Voltage Control in Image Forming Apparatus
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses face difficulties in controlling transfer voltage due to undetectable current leakage from conductive members without detection units, leading to inefficient toner transfer and image defects.
Innovation Solution
Incorporating a detection unit to monitor current flow in the transfer member and a control unit to adjust the transfer voltage based on detected current values, ensuring appropriate voltage settings for effective toner transfer and image fixation, even with current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conductive member is disposed upstream from the transfer portion without a detection unit, then the device complexity is reduced, but current leakage becomes undetectable leading to inappropriate transfer voltage control
Solution Approach 1:
The patent introduces a feedback mechanism by adding a detection unit that monitors current flow in the transfer member. The control unit receives detection results and adjusts the transfer voltage accordingly, creating a closed-loop control system that ensures reliable transfer voltage control while maintaining relatively simple device structure.
2Reliability
If a detection unit is added to monitor current flow in the transfer member, then transfer voltage control reliability is improved, but device complexity increases
Solution Approach 1:
The detection unit is strategically placed only at the transfer member location where current monitoring is most critical, rather than throughout the entire system. This localized approach provides necessary feedback for transfer voltage control while minimizing the increase in device complexity.
3Use of energy by moving object
If transfer voltage is not properly controlled due to undetectable current leakage, then energy consumption may be reduced, but image quality deteriorates due to transfer defects
Solution Approach 1:
The control unit uses real-time current detection feedback to dynamically adjust transfer voltage, ensuring optimal voltage levels that prevent transfer defects and maintain high image quality while avoiding excessive energy consumption through precise voltage 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
This solution enables precise control of transfer voltage, preventing image defects and ensuring consistent toner transfer onto the medium, regardless of current leakage paths, thereby improving the overall image forming process.
Implementation Method 1
a transfer voltage is applied to a transfer member disposed to face an image bearing member, such as a drum-shaped photosensitive member or intermediate transfer member, to electrostatically transfer a toner image borne on the image bearing member onto a transfer medium
Implementation Method 2
a detection unit configured to detect a current flowing in the transfer member when the voltage is applied from the transfer power source to the transfer member
Implementation Method 3
the transfer medium onto which the toner image is transferred at a transfer portion formed by the image bearing member and the transfer member is conveyed to a fixing unit and then heated and pressed by the fixing unit so that the toner image is fixed to the transfer medium
Data Source
AI summary
A control unit controls a transfer power source in such a manner that a current value detected by a detection unit is a predetermined value while a transfer medium is not held in a transfer portion, and the control unit sets a transfer voltage based on a voltage value applied from the transfer power source to a transfer member. Then, the transfer voltage is applied from the transfer power source to a transfer roller after the leading edge of the transfer medium in the conveyance direction for the transfer medium is held in the transfer portion and before the leading edge is held in a fixing portion. While the transfer voltage is applied, the control unit sets a voltage to be applied from the transfer power source to the transfer member based on the value of current detected by the detection unit.