Charging Roller Toner Collection via Potential Control
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Solution Overview
Problem
In image forming apparatuses using a simultaneous development and cleaning system, toner of opposite charging polarity can adhere to the charging member, affecting the charging capacity of the photosensitive drum, and existing methods to reverse toner polarity are not always successful, leading to incomplete collection and charging failures.
Innovation Solution
An image forming apparatus with a controller that executes a collection sequence using specific potential differences to move toner of opposite polarity from the charging member to the image bearing member and then to the developer bearing member, allowing regular polarity toner to be collected without reversing polarity, thereby preventing contamination of the charging member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the charging member is cleaned by turning off biases when the rear edge of the print area passes through, then toner of opposite polarity is transferred from the charging member to the photosensitive drum, but the toner may not be successfully reversed in polarity by rubbing action, leading to incomplete collection and re-adhesion
Solution Approach 1:
The patent applies preliminary action by turning off the charging bias before the rear edge of the print area reaches the charging member, and turning off the developing bias after the rear edge passes the developing member. This timing sequence ensures that toner is transferred to the photosensitive drum before cleaning begins, and the cleaning process completes before new toner is supplied, preventing incomplete polarity reversal and re-adhesion issues
Solution Approach 2:
The patent implements periodic action through cyclic bias control where the charging bias and developing bias are turned on and off in periodic cycles synchronized with the rotation of the photosensitive drum. This periodic switching enables systematic transfer and collection of toner particles, ensuring complete cleaning while maintaining charging capacity throughout the printing cycle
2Device complexity
If a cleaner-less system is used to reduce apparatus size and environmental impact, then the developer bearing member develops and cleans simultaneously, but toner of opposite polarity adheres to the charging member, affecting charging capacity
Solution Approach 1:
The patent merges the cleaning function into the developing process by using the developer bearing member to simultaneously develop the electrostatic latent image and collect toner of opposite polarity from the charging member. This integration eliminates the need for a separate cleaning device, reducing apparatus size while preventing toner adhesion through controlled bias switching that transfers toner to the photosensitive drum for subsequent collection
Solution Approach 2:
The patent changes the electrical parameters (bias voltages) of the charging and developing members to control toner movement. By adjusting the charging bias and developing bias in specific sequences, the system dynamically controls the polarity and movement of toner particles, enabling the charging member to transfer opposite polarity toner to the photosensitive drum without permanent adhesion, thus maintaining charging capacity in a compact cleaner-less design
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 collects toner without reversing its polarity, reducing charging roller contamination and maintaining the charging capacity of the photosensitive drum, even in the latter half of the cartridge's life, ensuring stable image formation.
Implementation Method 1
a charging member that is provided in contact with the image bearing member and charges the image bearing member
Implementation Method 2
setting a first potential difference to allow the developer of opposite polarity to move from the charging member to the surface of the image bearing member
Implementation Method 3
the toner of opposite charging polarity changes to toner of regular polarity by being rubbed by the developing roller that is applied with a bias lower than the surface potential of the photosensitive drum
Data Source
AI summary
An image forming apparatus includes a controller that executes a collection sequence to collect developer of opposite polarity adhering to a charging member. The controller executes the collection sequence by setting a first potential difference to allow the developer of opposite polarity to move from the charging member to an image bearing member, setting a second potential difference to allow the developer of opposite polarity to move from the image bearing member to a developer bearing member and to allow the developer of regular polarity to move from the developer bearing member to the image bearing member, setting a third potential difference to not allow the developer of regular polarity to move from the image bearing member to the charging member, and setting a fourth potential difference to allow the developer of regular polarity to move from the image bearing member to the developer bearing member.