Toner External Additive Size and Content for Charging Roller Purity
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Solution Overview
Problem
Conventional cleaner-less image forming apparatuses face issues with uneven charging and contamination of the charging roller due to the external additive in the toner, leading to charging abnormalities and abnormal images, especially during prolonged use.
Innovation Solution
The image forming apparatus incorporates a toner with a volume average particle diameter of the external additive between 5 nm and 50 nm and a content of 1.8% by mass or less, which reduces the likelihood of the external additive being released and contaminating the charging roller, and includes a developing device to collect transfer residual toner, thereby minimizing charging abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a contact charger is used to charge the image bearer, then charging efficiency is improved, but transfer residual toner causes uneven charging and contamination of the charging roller
Solution Approach 1:
The patent changes the particle size parameter of the external additive to 5-50 nm and controls its content to 1.8% by mass or less. This parameter optimization reduces the external additive's tendency to detach and contaminate the charging roller, thereby maintaining charging uniformity while preserving the efficiency of contact charging.
Solution Approach 2:
The patent applies local quality by creating a dual-function developing device: it performs both toner development and transfer residual toner collection. The collecting unit is integrated into the developing device, providing localized cleaning function at the image bearer surface without requiring a separate cleaner component.
2Ease of operation
If external additive is added to toner, then toner flowability and chargeability are improved, but external additive detaches and contaminates the charging roller during prolonged use
Solution Approach 1:
The patent optimizes the particle size of the external additive to 5-50 nm and controls its content to 1.8% by mass or less. This parameter optimization ensures that the external additive maintains toner chargeability and flowability while significantly reducing its tendency to detach and contaminate the charging roller during prolonged operation.
Solution Approach 2:
The patent uses a small amount of external additive (1.8% by mass or less) that serves its primary function of improving toner chargeability and flowability without causing long-term contamination issues. The controlled quantity ensures the additive is consumed or remains bound to the toner, preventing accumulation on the charging roller.
3Volume of moving object
If cleaner-less type is adopted for downsizing, then device size is reduced, but transfer residual toner accumulates causing charging abnormalities
Solution Approach 1:
The patent merges the functions of toner development and transfer residual toner collection into a single developing device. The collecting unit is integrated with the developing device, allowing it to perform both development and cleaning functions without requiring a separate cleaner component, thus achieving downsizing while maintaining reliability.
Solution Approach 2:
The developing device is designed with multi-functionality, serving both as a toner development unit and a transfer residual toner collection unit. This universal design eliminates the need for a separate cleaner, reducing device size while ensuring charging uniformity through continuous removal of transfer residual toner.
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 the accumulation of external additives on the charging roller, prevents charging failures, and reduces the occurrence of abnormal images by maintaining charging uniformity and cleanliness.
Implementation Method 1
a charger to charge the image bearer
Implementation Method 2
an electrostatic latent image is developed with a toner to form a toner image
Implementation Method 3
The toner image is transferred onto a transfer material such as paper
Data Source
AI summary
An image forming apparatus includes an image bearer, a charger, a developing device, and a transferor. The charger is disposed in contact with the image bearer to charge the image bearer. The developing device supplies toner to the image bearer to form a toner image on the image bearer. The transferor transfers the toner image on the image bearer to a recording medium or an intermediate transferor. The developing device collects transfer residual toner remaining on the image bearer after transfer of the toner image. The toner contains base particles and an external additive. The external additive has a volume average particle diameter of 5 nm or more and 50 nm or less. A content of the external additive is 1.8% by mass or less in the toner.