Image Forming Apparatus With Transfer Residual Toner Control
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Solution Overview
Problem
Cleanerless image forming apparatuses face challenges in effectively collecting and managing transfer residual toner, leading to potential retransfer issues and inefficiencies due to varying environmental conditions and toner charging abilities.
Innovation Solution
The apparatus employs a controller to manage transfer currents during transfer and non-transfer periods, adjusting the second transfer current to maintain a charge amount of transfer residual toner between -30 μC/g and -25 μC/g, utilizing a developing device to collect toner with a controlled potential difference, and optionally using a collection brush to manage positively charged toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging bias is increased to collect transfer residual toner, then the background potential difference increases and toner collection improves, but the charge amount of transfer residual toner becomes excessive causing retransfer issues
Solution Approach 1:
The charging bias is not kept constant but is dynamically adjusted based on operational conditions. The system switches between a first charging bias during transfer periods and a second charging bias during non-transfer periods, allowing optimal toner collection while preventing excessive charging that causes retransfer.
Solution Approach 2:
The system changes the charging bias parameter between different operational states. By setting the second charging bias to be lower than the first charging bias during non-transfer periods, the system maintains sufficient toner collection efficiency while controlling the charge amount to prevent retransfer.
2Ease of operation
If the apparatus uses a cleaner to remove transfer residual toner, then toner management is simplified, but the apparatus size increases and user maintenance becomes more complex
Solution Approach 1:
The system uses the developing device to perform the function of collecting transfer residual toner that would otherwise require a dedicated cleaner. The developing device automatically collects toner during normal operation without requiring separate cleaning mechanisms or user intervention.
Solution Approach 2:
The developing device is made multi-functional by having it perform both its primary function of forming toner images and the additional function of collecting transfer residual toner. This eliminates the need for a separate cleaner component while maintaining effective toner management.
3Productivity
If the transfer current is increased to improve transfer efficiency, then more toner is transferred to the transfer medium, but the charge amount of remaining toner increases causing collection difficulties
Solution Approach 1:
The transfer current is dynamically adjusted based on whether a transfer operation is currently being performed. During non-transfer periods, a second transfer current is applied that is optimized for maintaining proper charge levels on remaining toner, while during transfer periods, the first transfer current maximizes transfer efficiency.
Solution Approach 2:
The system applies different transfer currents in periodic cycles corresponding to transfer and non-transfer periods. This periodic switching allows the system to optimize for transfer efficiency during active transfer while maintaining collection reliability during idle periods.
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 enhances toner collection efficiency, reduces retransfer, and maintains apparatus performance across varying conditions, contributing to downsized and user-friendly operation.
Implementation Method 1
a charger to charge an image bearer such as a photoconductor
Implementation Method 2
a transfer device to transfer the toner on the photoconductor to a recording medium or an intermediate transferor
Implementation Method 3
The background potential difference between the charger and the photoconductor moves the toner adhered to the charger toward the photoconductor
Data Source
AI summary
An image forming apparatus includes a bearer, a charger charging the bearer at a charging position, a developing device forming an image at a developing position, a transferor transferring the image onto a transfer medium in a transfer period, a power source to flow a first current during the transfer period and a second current during a non-transfer period, and circuitry. The circuitry controls the power source to set a value of the second current to at least one of zero or a value having the same polarity as the first current and an absolute value different from that of the first current and set a charge amount of toner on the bearer between the charging position and the developing position to be from −30 μC/g to −25 μC/g.