Toner Bulk Density Control for Image Quality
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Solution Overview
Problem
In electrophotographic processes, the use of small toner particles leads to increased bulk density, causing blisters and image roughness due to voids and air permeability issues in coated papers, while controlling toner amount and density is challenging without compromising image quality.
Innovation Solution
An image forming method that specifies a toner amount range of 2.0 to 4.5 g/m2 for single-color images and 8.0 to 18 g/m2 for multi-color images, with a bulk density of 0.2 to 0.5 g/cm3, using a developer containing toners with a volume average particle size of 2 to 7 μm and a shape factor of 100 to 140, to maintain electrostatic binding and prevent toner scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small toner particles are used to improve resolution and image quality, then manufacturing precision is improved, but bulk density increases causing blisters and image roughness
Solution Approach 1:
The patent changes the bulk density parameter of toner particles from conventional high density (>0.5 g/cm³) to a controlled range of 0.2-0.5 g/cm³. This parameter change allows small particles (2-7 μm) to maintain low bulk density, preventing void formation and blisters while preserving high resolution image quality.
2Object-affected harmful factors
If toner bulk density is increased to reduce voids, then image roughness is reduced, but blisters occur due to smaller voids trapping moisture vapor
Solution Approach 1:
The patent optimizes the bulk density parameter to a specific range (0.2-0.5 g/cm³) that balances void size and distribution. This controlled parameter change creates optimal void structures that allow moisture vapor escape while maintaining smooth image surfaces, preventing both roughness and blisters.
3Manufacturing precision
If toner amount is increased to improve image coverage, then image quality is improved, but blisters and roughness worsen due to higher density accumulation
Solution Approach 1:
The patent changes the bulk density parameter of toner to 0.2-0.5 g/cm³, which allows increased toner amount application without proportional increase in void formation. This parameter change enables sufficient image coverage while maintaining smooth surfaces and preventing blisters.
4Manufacturing precision
If coated paper with high sheet gloss is used to improve image quality, then manufacturing precision is improved, but air permeability is reduced causing blisters during fixing
Solution Approach 1:
The patent changes the bulk density parameter of toner to compensate for the low air permeability of high-gloss coated paper. The optimized bulk density (0.2-0.5 g/cm³) creates a toner layer structure that facilitates moisture vapor escape through the paper, preventing blisters while maintaining image quality on glossy substrates.
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 method effectively suppresses blisters and image roughness by controlling toner density and amount, ensuring stable image formation without strict medium and mode-dependent toner control, thus improving image quality and process efficiency.
Implementation Method 1
a photoreceptor forms an electrostatic latent image by exposure
Implementation Method 2
the developer transfers a toner image on the photoreceptor
Implementation Method 3
fixing the unfixed toner image on the paper
Data Source
AI summary
An image forming method, including forming an unfixed toner image on the surface of paper by an electrophotographic process using a developer containing a toner, and fixing the toner image on the paper, wherein a toner amount of the unfixed toner image is in the range of about 2.0 to 4.5 g/m2 for a toner image formed using a toner of one color, and in the range of about 8.0 to 18 g/m2 for a toner image formed by layering toners of four or more colors, and a bulk density of the toner is in the range of about 0.2 to 0.5 g/cm3.