Developing Sleeve Toner Charge Control via AC Voltage
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face issues with excessive toner charging, leading to image defects like fogging and density abnormalities, particularly in low-temperature and low-humidity environments, due to insufficient regulation of toner charge on the developing sleeve.
Innovation Solution
The apparatus incorporates a developing sleeve with a surface layer containing a urethane resin with a carbonate bond and a tertiary amine structure, which donates and accepts charge through frictional contact, and a controller that applies an AC voltage differently during image forming and non-image forming periods to manage toner charging effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface layer containing quaternary ammonium base or tertiary amine group is used to enhance toner charge donating ability, then toner charge capability is improved, but excessive charging occurs in low-temperature and low-humidity environments causing image defects
Solution Approach 1:
The patent introduces an environment sensing mechanism that detects temperature and humidity parameters, and a control mechanism that adjusts the AC voltage amplitude applied to the developing sleeve based on environmental conditions. In low-temperature and low-humidity environments, the control mechanism reduces the AC voltage amplitude to prevent excessive toner charging, while maintaining sufficient charge capability in normal environments through optimized AC voltage application during non-image forming periods.
2Object-affected harmful factors
If AC voltage is applied to developer carrying member during non-image forming period, then excessive charging is suppressed, but device complexity increases
Solution Approach 1:
The patent applies AC voltage to the developing sleeve periodically during non-image forming periods rather than continuously. The control mechanism switches between applying AC voltage during idle periods and stopping during image forming periods, creating a periodic action pattern that suppresses excessive charging without requiring complex continuous control systems.
Solution Approach 2:
The control mechanism automatically adjusts the AC voltage application based on environmental sensor inputs and operational state detection, enabling the system to self-regulate toner charging without manual intervention. The environment sensing and control mechanisms work autonomously to maintain optimal charging conditions.
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 configuration effectively suppresses excessive toner charging, maintaining sufficient charge for developing while preventing image defects, ensuring stable and high-quality printing across varying environmental conditions.
Implementation Method 1
the surface layer has an electron donating portion that mainly donates charge to the developer when the developer and the surface layer make frictional contact to exchange charge and an electron accepting portion that mainly accepts charge from the developer when the developer and the surface layer make frictional contact to exchange charge
Implementation Method 2
the controller applies an AC voltage to the developer carrying member during a period in which an image forming operation is not performed and the developer carrying member is driven, the AC voltage being different from that applied during an image forming period
Implementation Method 3
a power source that applies a voltage to the developer carrying member
Data Source
AI summary
An image forming apparatus includes a developer carrying member that bears and conveys developer. The developer carrying member has at least a base and a surface layer, with the surface layer having an electron donating portion that mainly donates charge to the developer when the developer and the surface layer make frictional contact to exchange charge and an electron accepting portion that mainly accepts charge from the developer when the developer and the surface layer makes frictional contact to exchange charge. A controller applies an AC voltage to the developer carrying member during a period in which an image forming operation is not performed and the developer carrying member is driven, with the AC voltage being different from that applied during an image forming period, and a rotating speed of the developer carrying member during a non-image forming period is slower than that during an image forming period.