Dynamic Charging Voltage Control for Image Flow Suppression
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Solution Overview
Problem
In electrophotographic image forming apparatuses, there is a trade-off between suppressing end portion contamination and image flow, where increasing the discharge amount to address potential differences between the photosensitive member's surface potential in sheet-passing and non-sheet-passing regions can lead to image flow defects, and reducing this discharge amount may result in end portion contamination.
Innovation Solution
An image forming apparatus that includes a controller to adjust the charging and developing voltages based on the electric resistance value of the transfer member, increasing the voltage when the resistance value decreases to maintain a consistent potential difference and reduce contamination, while minimizing the discharge amount to prevent image flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the discharge amount is increased to eliminate potential difference between sheet-passing and non-sheet-passing regions, then end portion contamination is suppressed, but image flow occurs
Solution Approach 1:
The charging voltage is dynamically adjusted based on the resistance value of the transfer member. When the resistance value changes (e.g., decreases over time), the charging voltage is modified accordingly to maintain optimal potential difference elimination without excessive discharge. This dynamic adjustment resolves the contradiction by adapting the discharge amount to current conditions rather than using a fixed high discharge level.
Solution Approach 2:
The invention changes the parameter of charging voltage in response to changes in the transfer member's resistance value. By monitoring resistance value and adjusting charging voltage accordingly, the system maintains sufficient discharge to eliminate potential differences and prevent end portion contamination while avoiding excessive discharge that would cause image flow.
2Object-affected harmful factors
If the charging voltage is increased to maintain potential difference elimination, then end portion contamination is reduced, but discharge amount increases causing image flow
Solution Approach 1:
The system uses feedback from the resistance value detection to adjust the charging voltage. By continuously monitoring the transfer member's resistance and modifying the charging voltage based on this feedback, the system achieves the minimum necessary discharge to eliminate potential differences without the excessive discharge that would cause image flow and energy loss.
Solution Approach 2:
The charging voltage parameter is changed in response to detected resistance value changes. This dynamic parameter adjustment ensures that the discharge amount is optimized - sufficient to eliminate potential differences and prevent end portion contamination, but not excessive enough to cause image flow or unnecessary energy loss.
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 suppresses end portion contamination while minimizing image flow by dynamically adjusting voltages in response to changes in the transfer member's resistance value, enhancing the overall image forming process.
Implementation Method 1
a surface of an electrophotographic photosensitive member is electrically charged substantially uniformly by a charging means, so that a dark-portion potential is formed on the surface of the photosensitive member
Implementation Method 2
the charged surface of the photosensitive member is exposed to light by an exposure means, so that a light-portion potential is formed on the surface of the photosensitive member, and an electrostatic latent image is formed on the photosensitive member by a contrast between the dark-portion potential and the light-portion potential
Implementation Method 3
toner is deposited on the electrostatic latent image, formed on the photosensitive member, by a developing means, so that a toner image is formed on the photosensitive member
Implementation Method 4
a transfer voltage of an opposite polarity to a normal charge polarity of the toner is applied, so that the toner image on the photosensitive member is electrostatically transferred onto the recording material
Data Source
AI summary
An image forming apparatus includes a photosensitive member, a charging member, a charging power source, a developing member, a transfer member, a transfer power source, an acquiring portion, and a controller. The controller controls a charging voltage to be a first charging voltage when an electric resistance value of the transfer member is a first resistance value and to be a second charging voltage not less than the first charging voltage in absolute value when the electric resistance value is a second resistance value lower than the first resistance value, and so that a change amount of the charging voltage when the electric resistance value is changed from the second resistance value to a third resistance value lower than the second resistance value is greater than a change amount of the charging voltage when the electric resistance value is changed from the first resistance value to the second resistance value.