Electrostatic Toner Particle Size Distribution for Image Quality
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Solution Overview
Problem
Existing electrostatic image developing toners with small diameters and narrow particle size distributions face challenges in maintaining high-quality image formation over time, as they tend to degrade in image quality and are difficult to remove from photoconductors, leading to issues like image fogging and poor cleaning efficiency.
Innovation Solution
A toner with a specific number average particle diameter range of 3.5 µm to 6.5 µm, a variation coefficient of 22.0 to 35.0, and a particle size distribution of 40% to 59% in the 4.0 µm to 8.0 µm range, combined with a two-component developer and a cleaning unit featuring a first and second cleaning blade, effectively addresses the challenges by ensuring excellent removability and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If toner particles with small diameter and narrow particle size distribution are used, then image sharpness and density are improved, but image quality degrades over time and cleaning efficiency decreases
Solution Approach 1:
The patent optimizes the particle size distribution parameters of toner particles, specifically setting the volume average particle diameter to 4.0-6.0 µm and controlling the particle size distribution so that 90% by mass falls within D(3√2)-1 to 3√2D. This parameter optimization enables small particles to provide sharp images while maintaining stability over time through controlled reuse.
Solution Approach 2:
The patent performs preliminary classification of toner particles by size before use, ensuring that the toner contains sufficient small particles (4.0-8.0 µm range at 40-59% by number) for high-resolution imaging while maintaining an overall distribution that prevents degradation during reuse. This preliminary sizing action prevents later quality issues.
2Quantity of substance
If toner particles with small diameter are used, then image density is improved, but removability from photoconductor surface deteriorates
Solution Approach 1:
The patent changes the particle size parameters to a specific range (4.0-6.0 µm volume average diameter) and controls the distribution so that 40-59% of particles by number are in the 4.0-8.0 µm range. This optimized parameter range provides sufficient small particles for high density images while maintaining particles large enough to be effectively removed by cleaning blades.
Solution Approach 2:
The patent uses a controlled proportion of small particles (40-59% in the 4.0-8.0 µm range by number) rather than exclusively small particles. This partial use of small particles achieves high image density while the presence of larger particles in the distribution maintains ease of removal, balancing both requirements.
3Productivity
If toner particles are collected and reused, then productivity is improved, but image quality and cleaning efficiency degrade
Solution Approach 1:
The patent optimizes particle size parameters (volume average diameter 4.0-6.0 µm, with 90% of particles in D(3√2)-1 to 3√2D range) that remain stable during collection and reuse. This parameter optimization ensures that reused toner maintains consistent imaging performance, enabling high productivity through multiple reuse cycles without quality degradation.
Solution Approach 2:
Instead of using large particles that are easy to handle but poor for high-resolution imaging, the patent inverts the approach by using small particles (4.0-6.0 µm volume average) that provide excellent image quality. The controlled particle size distribution ensures these small particles can be effectively reused without the usual quality degradation, reversing the conventional wisdom that small particles are unsuitable for reuse.
4Manufacturing precision
If fine particles are used for high-resolution images, then image sharpness is improved, but cleaning blade effectiveness decreases
Solution Approach 1:
The patent changes the particle size parameters to a specific range (4.0-6.0 µm volume average diameter) and controls the distribution so that 40-59% of particles by number are in the 4.0-8.0 µm range. This optimized parameter range provides sufficient small particles for high-resolution imaging while maintaining particles large enough to be effectively removed by cleaning blades.
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
The solution enables the formation of high-quality images with excellent sharpness and density, prevents image fogging, and maintains cleaning efficiency over a long period, effectively utilizing reused toner particles while minimizing environmental impact.
Implementation Method 1
electrostatic image developing toner
Implementation Method 2
cleaning blade and a cleaning roller whose surface is covered with an abrasive
Data Source
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AI summary
To provide a toner including: toner particles which comprise: a colorant, a releasing agent, and a binder resin, wherein the number average diameter of the toner particles is in the range of from 3.5 μm to 6.5 μm where the number average diameter (D1) is determined by the Coulter method, the variation coefficient of the number distribution of the toner particles is in the range of 22.0 to 35.0 where the variation coefficient is found by dividing the standard deviation of the number distribution by the number average diameter (D1), and 40% by number to 59% by number of the toner particles are in 4.0 μm to 8.0 μm in diameter.