Variable Frequency Filter for AC Charge Discharge Current Control
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Solution Overview
Problem
Existing image forming apparatuses using AC charge methods face challenges in accurately controlling discharge current due to changes in environmental factors like temperature and humidity, leading to reduced photoconductor drum life and non-uniform charging.
Innovation Solution
An image forming apparatus with a charging member that applies a superposed DC and AC voltage, equipped with a detector, extraction unit, adjustment unit, and acquisition unit to accurately control the AC voltage by adjusting the frequency band of the discharge current component based on environmental information, ensuring precise discharge current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed frequency band filter is used to extract discharge current component, then the control method is simple, but the detection accuracy deteriorates when environmental factors change
Solution Approach 1:
The patent applies dynamics by making the filter frequency band variable rather than fixed. The frequency band is dynamically adjusted based on detected environmental factors (temperature, humidity) to track the changing discharge current component frequency, thereby maintaining high detection accuracy under varying environmental conditions while avoiding the need for complex real-time signal processing
Solution Approach 2:
The patent changes the parameter of filter frequency band according to environmental conditions. By detecting temperature and humidity and using these to determine appropriate frequency bands, the system adapts the extraction parameters to match the current environmental state, ensuring accurate discharge current detection without requiring complex adaptive algorithms
2Manufacturing precision
If AC voltage is applied to charging member, then charge uniformity is improved, but photoconductor drum life decreases due to discharge
Solution Approach 1:
The patent implements feedback by continuously detecting the discharge current component frequency and using this information to adjust the filter frequency band. This closed-loop control ensures that the system maintains optimal extraction parameters, thereby accurately controlling the discharge current to protect the photoconductor drum while preserving charge uniformity
Solution Approach 2:
The patent replaces mechanical/sharp-based discharge control with an electrical signal processing approach. Instead of physically controlling discharge through mechanical means, the system uses electrical field manipulation and signal extraction to control and monitor discharge current, thereby extending photoconductor life while maintaining charge quality
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 highly accurate detection and control of discharge current even under changing environmental conditions, extending the life of the photoconductor drum and maintaining uniform charging for high-quality, long-term image formation.
Implementation Method 1
a charging member configured to charge the image-bearing member by receiving a charge voltage in which a direct-current voltage and an alternating-current voltage are superposed on each other
Implementation Method 2
a detector configured to detect a current flowing through the charging member when the power source applies the charge voltage to the charging member
Implementation Method 3
an extraction unit configured to extract, from the current detected by the detector when the charge voltage is applied to the charging member, a current in a frequency band including a discharge current component
Data Source
AI summary
An image forming apparatus includes an image-bearing member, which is charged by a charge voltage in which direct and alternating-current voltages are superposed on each other. A toner image is formed on the charged image-bearing member. A current flowing through the charging member is detected when the charge voltage is applied to the charging member. A current, in a frequency band including a discharge current component, is extracted from the detected current. The alternating-current voltage is adjusted based on the current extracted by an extraction unit. Environmental information is acquired. Based on the environmental information acquired by an acquisition unit, a frequency band for extraction performed by the extraction unit is set.