Toner Adherence Control for Stable Transfer
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Solution Overview
Problem
The downsizing of toner particles for improved image quality leads to decreased flowability, causing issues such as flocculation, reverse transfer, and uneven image formation, particularly in full-color image forming apparatuses, where existing solutions fail to adequately prevent reverse transfer and ensure stable toner transferability.
Innovation Solution
An image forming method using a toner with specific adherence properties, where the developing roller diameter is between 8 to 15 mm, and the toner has adherence Fh of 15 to 50 nN to a flat surface and adherence Fr of 100 to 400 mN among particles, satisfying certain formulaic relations, ensuring stable transfer and preventing reverse transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If toner particle diameter is reduced to improve image quality, then image quality is improved, but toner flowability decreases causing flocculation and reverse transfer
Solution Approach 1:
The invention changes the physical and chemical parameters of the toner particles, specifically controlling particle diameter within 3-7 μm, adherence to flat surface (Fh) within 15-50 nN, and adherence among particles (Fr) within 100-400 mN. These parameter adjustments optimize both image quality and flowability by preventing flocculation while maintaining stable transfer characteristics.
Solution Approach 2:
The invention uses composite toner particles comprising a core particle and a shell layer. The core particle provides the base properties for image formation, while the shell layer (0.01-2.0 μm thick) modifies surface characteristics to control adherence properties. This composite structure enables simultaneous optimization of flowability and transfer stability.
2Volume of moving object
If developing roller diameter is reduced to downsize the device, then device size is reduced, but toner supply rate decreases causing insufficient toner followability
Solution Approach 1:
The invention optimizes the developing roller diameter parameter to within 8-15 mm, which balances device downsizing with adequate toner supply rate. This parameter adjustment ensures sufficient toner followability while maintaining compact device dimensions suitable for one-component developing systems.
3Reliability
If toner adherence to flat surface is increased to prevent reverse transfer, then reverse transfer is prevented, but toner transferability deteriorates
Solution Approach 1:
The invention precisely controls the adherence to flat surface (Fh) parameter within 15-50 nN through adjustment of particle diameter, shell layer thickness, and adherence among particles (Fr). This optimized parameter range creates a balance where toner adheres sufficiently to prevent reverse transfer during transfer, yet maintains adequate transferability for complete image transfer.
Solution Approach 2:
The invention creates dynamic adherence characteristics where the toner's adherence properties adapt to different operational phases. During transfer, the controlled adherence prevents reverse transfer, while during development and supply, the parameters enable adequate flow and transfer. The shell layer composition and thickness are optimized to provide this dynamic behavior.
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 secures stable toner transferability, prevents reverse transfer, and produces high-quality images without concentration or color unevenness, even in full-color image forming apparatuses, by controlling toner adherence and particle diameter.
Implementation Method 1
a toner having an adherence Fh (nN) to a flat surface satisfying the relation represented by formula (1) and an adherence Fr (mN) among toner particles satisfying the relation represented by formula (2)
Data Source
AI summary
Objects of the present invention are to provide an image forming method and image forming apparatus which can secure stable toner transferability, prevent reverse transfer of the toner back to a latent image bearing member, have excellent fixing ability and produce high-quality images. The image forming method includes a one-component developing step with a toner and transferring step with an intermediate transfer member, wherein the developing step uses a developing roller having a diameter of 8 mm to 15 mm, and the toner has an adherence Fh (nN) of the toner to a flat surface satisfying the relation represented by the formula (1) and adherence Fr (mN) among the toner particles satisfying the relation represented by the formula (2):15≦Fh≦50 (1)100≦Fr≦400 (2).