Toner Surface Fixing Ratio and Shear Control for Density Uniformity
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Solution Overview
Problem
Existing toners with excellent development durability may not be durable under certain process conditions, leading to potential unevenness and density unevenness in image formation.
Innovation Solution
A developing device and process cartridge that maintain high charging performance of the developer over a long period by increasing the shear applied to the toner, while ensuring a high fixing ratio of inorganic particles on the toner surface and an appropriate aspect ratio of the toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic particles are externally added to the toner surface to improve development durability and storage stability, then high-temperature storage stability and printing durability are improved, but density unevenness due to potential unevenness occurs under certain process conditions
Solution Approach 1:
The patent changes the physical and chemical parameters of the inorganic particles, specifically controlling the particle size distribution (D50: 0.3-1.0 μm, D90/D50 ratio: 1.05-1.30) and surface properties. This optimization ensures sufficient friction for charging while preventing aggregation that causes density unevenness
Solution Approach 2:
The patent creates a composite toner structure by externally adding inorganic particles to the toner surface. The composite consists of the base toner material combined with specific inorganic particles (such as silica, titania, or alumina) that provide both improved durability and controlled friction characteristics
2Quantity of substance
If friction resistance of the toner is improved to increase charge quantity, then charging performance is improved, but density unevenness due to potential fluctuations occurs
Solution Approach 1:
The patent optimizes the particle size parameters of inorganic particles (D50: 0.3-1.0 μm, D90/D50 ratio: 1.05-1.30) to achieve the right balance between friction resistance and uniformity. This controlled parameter change increases charge quantity while preventing potential fluctuations that cause density unevenness
3Quantity of substance
If shear applied to the toner is increased to maintain charging performance, then charge quantity is maintained, but development streaks and toner dropout may occur
Solution Approach 1:
The patent changes the surface friction parameters by adding inorganic particles with specific size distribution. This modification allows the toner to withstand increased shear forces during charging while maintaining cohesive properties that prevent development streaks and dropout
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 effectively suppresses the occurrence of density unevenness due to potential fluctuations, maintaining high charging performance and preventing development streaks and toner dropout.
Implementation Method 1
since the main charging means of the toner is based on friction, where the friction resistance of the toner is improved, the shear (friction opportunity and frictional force) with the charging member can be increased, leading to an increase in the charge quantity of the toner
Implementation Method 2
Japanese Patent Application Publication No. 2006-146056 discloses a toner in which inorganic particles are externally added to the toner surface to obtain a toner excellent in high-temperature storage stability and printing durability
Data Source
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AI summary
A developer on a developer bearing member includes a toner having a toner particle including a binder resin and an inorganic particle present on the surface of the toner particle. A fixing ratio of the inorganic particle to the surface of the toner particle is 80% or more. The aspect ratio of the toner is 0.90 or more. Where a contact pressure of a regulating member, which regulates the developer on the developer bearing member, against the developer bearing member is denoted by N (gf/mm) and a contact pressure of the supplying member, which is in contact with the developer bearing member and supplies the developer to developer bearing member, against the developer bearing member is denoted by D (gf/mm), the following expressions are satisfied: D + 2 × N - 6 ≥ 0, 1.5 ≤ N ≤ 4.0, and 2.0 ≤ D ≤ 3.5.