Charging Roller Toner Collection Mechanism
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Solution Overview
Problem
Conventional 4-cycle image forming apparatuses require a contact-and-separation drive mechanism for the charging roller, which hinders scale-down and cost reduction, and often fail to reliably collect after-transfer remaining toner due to incomplete charging.
Innovation Solution
A developer collecting/charging device with a roller positioned close to the transfer member but not in contact, using specific voltage waveforms to collect and charge after-transfer remaining toner to a reverse polarity without a cleaning device or contact-and-separation mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning device is provided for the transfer belt to collect remaining toner, then the collection of after-transfer remaining toner is improved, but the device complexity increases due to the need for a contact-and-separation drive mechanism
Solution Approach 1:
The invention extracts the cleaning function from a separate cleaning device and integrates it into the charging roller itself. The charging roller performs both charging and cleaning functions, eliminating the need for a dedicated cleaning device with its own contact-and-separation drive mechanism. This reduces device complexity while maintaining the reliability of toner collection.
Solution Approach 2:
The invention merges the cleaning function with the charging roller function. The charging roller is designed to both charge the photoconductor and collect remaining toner from the transfer belt through its positioning and operational characteristics, combining multiple functions into a single component to reduce overall system complexity.
2Reliability
If the charging roller is positioned close to the transfer belt to facilitate toner collection, then the collection efficiency is improved, but the risk of disturbing the toner image increases
Solution Approach 1:
The invention applies local quality by positioning the charging roller to interact selectively with different regions. The roller is positioned to collect toner from the transfer belt area while maintaining appropriate spacing or positioning to avoid disturbing the freshly transferred toner image on the photoconductor, thus achieving both collection efficiency and image protection.
Solution Approach 2:
The charging roller acts as an intermediary element between the transfer belt and the photoconductor. It facilitates the collection of remaining toner from the transfer belt while its design and positioning ensure it does not directly contact or disturb the toner image on the photoconductor, mediating between these two components to achieve both objectives.
3Reliability
If a contact-and-separation drive mechanism is provided for the charging roller, then the positioning control is improved, but the device complexity and cost increase
Solution Approach 1:
The charging roller is designed to perform its function of collecting remaining toner through its inherent rotational motion and positioning during the normal image formation process. It utilizes the existing drive system that rotates the photoconductor and transfer belt, and the charging roller's positioning is automatically managed through the interaction of these components, eliminating the need for a separate contact-and-separation drive mechanism.
4Manufacturing precision
If the charging roller is kept withdrawn away from the transfer belt to avoid disturbing the toner image, then the image quality is protected, but the collection of after-transfer remaining toner becomes unreliable
Solution Approach 1:
The charging roller is designed with dynamic positioning capabilities where its effective position relative to the transfer belt changes during different phases of operation. During the collection phase, it is positioned to facilitate toner collection, while during image formation, its positioning naturally prevents disturbance to the toner image, achieving both objectives through dynamic operational characteristics.
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
Enables reliable reverse transfer and collection of after-transfer remaining developer to the image carrier, eliminating the need for a cleaning device and contact-and-separation drive mechanism, thus facilitating scale-down and cost reduction of the image forming apparatus.
Implementation Method 1
a voltage in which an AC voltage is superimposed on a DC voltage is applied to the after-transfer remaining toner by a charging roller so that the after-transfer remaining toner is uniformly charged to a polarity reverse to a normal polarity
Implementation Method 2
part of the after-transfer remaining toner is temporarily collected by the developer collecting/charging member that is in the developer-collecting mode
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
According to the present invention, after-transfer remaining toner is reversely transferred from a transfer member (16) to an image carrier (14) and thereby collected with reliability. A toner collecting/charging device (50) for temporarily collecting and charging the after-transfer remaining toner remaining on the transfer member (16) includes a toner collecting/charging roller (53) which is provided in such proximity to the transfer member (16) as not to make contact with a primarily transferred toner image, and which has a collecting function of temporarily collecting the after-transfer remaining toner and a charging function of charging the after-transfer remaining toner to a specified polarity, power supplies which are so connected that a voltage in which an AC voltage (54,56) is superimposed on a DC voltage (60) is applied to the roller (53), and a selector switch (58) for changing a waveform of the AC voltage so that the toner collecting/charging roller (53) is switched between a toner-collecting mode and a toner-releasing mode.