Photoconductor Charging Current Detection for Ghost Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the phenomenon of 'ghost' occurs due to potential steps on the photoconductor surface, leading to image density differences, and existing methods to control ghost through pre-exposure devices cause photoconductor deterioration and fail to set appropriate light amounts due to variations in resistance values and environmental changes.
Innovation Solution
An image forming apparatus with a control unit that detects charging currents before and after pre-exposure, adjusting the light input from a pre-exposure device to maintain a constant light amount, decelerating photoconductor deterioration by setting the pre-exposure current based on detected charging currents and potential changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pre-exposure device irradiates the photoconductor surface to control ghost, then ghost occurrence is reduced, but photoconductor deterioration is accelerated
Solution Approach 1:
The system detects charging current variations caused by potential steps on the photoconductor surface and uses this feedback to dynamically adjust the pre-exposure light amount, achieving ghost control while minimizing unnecessary light irradiation that would accelerate photoconductor deterioration
Solution Approach 2:
The invention changes the light amount parameter of the pre-exposure device based on detected charging current variations, adjusting it to be just sufficient to eliminate potential steps and ghost, rather than using fixed high-intensity irradiation that causes deterioration
2Duration of action of stationary object
If the pre-exposure light amount is reduced to decelerate photoconductor deterioration, then photoconductor lifespan is extended, but ghost control becomes insufficient
Solution Approach 1:
By continuously monitoring charging current variations that indicate potential step formation, the system provides feedback to adjust pre-exposure light amount dynamically, ensuring sufficient ghost control even with reduced overall light exposure to extend photoconductor life
3Reliability
If the pre-exposure light amount is adjusted individually for each photoconductor unit, then appropriate ghost control is achieved, but system complexity increases
Solution Approach 1:
The system automatically detects charging current variations and adjusts pre-exposure light amount without requiring manual individual calibration of each photoconductor unit, achieving accurate ghost control while keeping the system simple through self-adjusting operation
Solution Approach 2:
The detection of charging current variations provides automatic feedback that eliminates the need for complex pre-adjustment procedures for each photoconductor unit, simplifying the system while maintaining accurate ghost 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
Effectively reduces ghost occurrences while decelerating photoconductor deterioration by maintaining a consistent light exposure, even with changes in resistance values and environmental conditions, ensuring stable image formation.
Implementation Method 1
a pre-exposure device having a light source, such as LED... configured to irradiate the surface of the photoconductor with the light output from the light source
Implementation Method 2
a charging unit configured to charge the photoconductor at a charging position when applied a DC voltage... in a DC charging system in which charging is conducted when a DC voltage is applied to a charging roller
Implementation Method 3
a transfer unit configured to transfer the toner image formed on the photoconductor by the toner image forming unit by applying transfer voltage to member to be transferred
Data Source
AI summary
When attachment of an unused photoconductor unit is detected, a mode is executed in which, during non-image formation, a first current flowing in a charging roller is detected when a photoconductor is re-charged without irradiation of light by a pre-exposure device after being charged and passing through a transfer position during non-image formation, and a second current flowing in the charging roller is detected when the photoconductor is re-charged with irradiation of light by the pre-exposure device after being charged and passing through the transfer position, and a current supplied to an LED lamp during image formation is controlled in accordance with detection results.