Photoreceptor Charging Control via Current Saturation Detection
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Solution Overview
Problem
Current image forming apparatuses face challenges in determining the optimal DC voltage for charging photoreceptors without damaging the surface, as existing methods require complex measurements of surface potential, which is difficult in compact designs and can lead to uneven surface potential and reduced lifespan.
Innovation Solution
An image forming apparatus and method that measures the current applied to a photoreceptor to find a current saturation point, allowing for controlled DC charging without measuring surface potential, using a combination of fixed DC and varied AC power to determine the appropriate charging voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AC+DC charging scheme is used to achieve high uniformity of surface potential, then charging uniformity is improved, but discharge damage to photoreceptor surface increases
Solution Approach 1:
The patent changes the charging parameters by using only DC voltage without AC voltage, and controls the DC voltage to be below a threshold value to prevent discharge. This parameter change resolves the contradiction by achieving acceptable surface potential uniformity through controlled DC charging while avoiding the discharge damage caused by AC+DC charging.
2Duration of action of stationary object
If DC charging scheme is used to extend photoreceptor lifespan, then photoreceptor durability is improved, but surface potential uniformity deteriorates
Solution Approach 1:
The patent introduces a specific parameter control mechanism by limiting the DC voltage to below a threshold value. This parameter change enables DC charging to maintain photoreceptor lifespan while achieving acceptable surface potential uniformity, resolving the contradiction between durability and charging quality.
3Measurement precision
If separate sensor is used to measure surface potential for optimal DC voltage determination, then charging precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex surface potential measurement system by using a simplified approach: applying DC voltage below a threshold and measuring current saturation. This extraction of unnecessary complexity resolves the contradiction by achieving practical charging control without expensive and complex surface potential sensors.
Solution Approach 2:
The patent substitutes the mechanical/electrical surface potential measurement system with an electrical current measurement system. By measuring current saturation instead of surface potential directly, the system achieves charging control with simpler and less expensive components, resolving the complexity issue.
4Manufacturing precision
If DC voltage is increased to improve surface potential uniformity, then charging uniformity is improved, but discharge damage increases
Solution Approach 1:
The patent changes the voltage parameter by establishing and maintaining DC voltage below a specific threshold value. This parameter control prevents discharge damage while achieving sufficient surface potential uniformity for practical imaging applications, resolving the contradiction between uniformity and damage prevention.
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 enables accurate and efficient charging of photoreceptors without surface potential measurement, improving lifespan and uniformity while simplifying the charging process in compact devices.
Implementation Method 1
a measurement unit configured to measure a current provided to the charging member
Implementation Method 2
a charging member configured to charge a photoreceptor; a power supply configured to provide charging power to the charging member
Data Source
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AI summary
An image forming apparatus includes a charging member configured to charge a photoreceptor, a power supply configured to provide charging power to the charging member, a measurement unit configured to measure a current provided to the charging member, and a controller configured to search for a current saturation point of the charging member using the current value measured by the measurement unit in a state in which fixed direct current (DC) power and varied alternating current (AC) power are supplied to the charging member, and control the power supply to perform a charging operation with only DC power corresponding to the searched current saturation point.