Transfer Body Voltage Control for Image Quality
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Solution Overview
Problem
In electrophotography-type image forming apparatuses, developer images are prone to deterioration when the sheet is excessively pulled downstream, and the attractive force from transfer bodies is insufficient when the sheet is not in contact with multiple drums, leading to image degradation.
Innovation Solution
An image forming apparatus with a controller that applies a higher voltage to the most downstream transfer body when the sheet is not in contact with any drum but the most downstream photoconductive drum, ensuring a sufficient attractive force to prevent image deterioration by adjusting the voltage applying mode based on detection results from a detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheet feeding speed at the fuser unit is set lower than at the photoconductive drums to prevent excessive downstream pulling, then the sheet is bent buckling and the trailing end is urged upstream by restoring force, but the attractive force from transfer bodies becomes insufficient when the sheet is not in contact with multiple drums, leading to image deterioration
Solution Approach 1:
The voltage applied to the transfer body is dynamically adjusted based on the sheet contact state. When the sheet is not in contact with multiple photoconductive drums, the controller increases the voltage to the transfer body to compensate for the reduced attractive force, thereby maintaining reliable image transfer under varying operational conditions
Solution Approach 2:
The electrical parameter (voltage) of the transfer body is changed in response to changes in the mechanical state (sheet contact condition). By detecting whether the sheet is in contact with one or multiple drums and adjusting the voltage accordingly, the system maintains sufficient attractive force to prevent image deterioration
2Reliability
If a higher voltage is applied to the most downstream transfer body when the sheet is not in contact with multiple drums, then the attractive force is sufficient to prevent image deterioration, but the device complexity increases due to voltage mode switching control
Solution Approach 1:
The controller detects the sheet contact state with photoconductive drums and uses this feedback information to determine the appropriate voltage mode. This feedback mechanism enables automatic adjustment of the transfer body voltage to match operational conditions, ensuring stable image transfer without manual intervention
Solution Approach 2:
The voltage control system transitions from a static fixed-voltage approach to a dynamic adaptive-voltage approach. The system automatically switches between voltage modes based on real-time detection of sheet contact conditions, maintaining optimal transfer performance across different operational scenarios
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 effectively prevents the trailing end of the sheet from moving upstream, thereby maintaining image quality by ensuring a consistent attractive force during image transfer, even when the sheet is not in contact with multiple drums.
Implementation Method 1
the attractive force applied to the sheet is an electrostatic attractive force generated when the transfer bodies are supplied with voltages
Data Source
AI summary
An image forming apparatus is provided, which includes photoconductive drums arranged along a sheet conveyance direction, transfer bodies each disposed to face a corresponding one of the photoconductive drums, a fuser unit disposed downstream relative to a most downstream photoconductive drum in the sheet conveyance direction and configured to feed a sheet at a feeding speed lower than a feeding speed of the most downstream photoconductive drum, and a controller configured to, when the sheet is not in contact with any photoconductive drum but the most downstream photoconductive drum, perform a specific voltage applying mode to apply, to a most downstream transfer body in the sheet conveyance direction, a higher voltage than when the sheet is in contact with two or more photoconductive drums.