Developing Roller Surface Layer with Solubility Parameter Matching
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Solution Overview
Problem
Conventional developing rollers with surface layers containing conductive inorganic fine particles suffer from particle aggregation and separation, leading to unstable toner charging and transporting properties, especially under environmental variations, resulting in image irregularities and increased device complexity.
Innovation Solution
A developing roller with a surface layer composed of a binder resin having a solubility parameter (SP) value between 7.5 and 9.0, combined with roughness-imparting particles from a resin with an SP value differing by no more than 2, dispersed to prevent particle aggregation and separation, ensuring stable toner charging and transporting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conductive inorganic fine particles are dispersed in the resin layer of the developing roller, then toner transporting property is improved, but particles wear off and come off from the surface after long use, causing failure to provide sufficient toner charging and transporting property
Solution Approach 1:
The patent changes the material parameters of the surface layer by using organic fine particles with specific solubility parameter values (7.5-9.0) and specific gravity (1.05-1.20 g/cm³), replacing conventional inorganic particles. This parameter change ensures the particles remain embedded in the resin layer without wearing off, maintaining both toner transporting property and charging stability over time.
Solution Approach 2:
The patent creates a composite surface layer combining organic fine particles with specific resin materials. The composite structure of organic particles dispersed in a compatible resin matrix provides both the necessary surface roughness for toner transport and the adhesion strength to prevent particle loss, resolving the contradiction between productivity and reliability.
2Reliability
If a system to measure ambient environmental factors is added to stabilize developing property, then charging stability against environmental variations is improved, but device becomes bulky and costs increase due to increase in number of parts
Solution Approach 1:
The developing roller surface layer is designed to self-stabilize toner charging properties through the inherent characteristics of the organic fine particles and resin combination. The material composition automatically compensates for environmental variations without requiring external measurement or control systems, achieving reliability improvement while reducing device complexity.
Solution Approach 2:
By changing the material parameters of the surface layer to use organic particles with specific solubility parameters and specific gravity ranges, the system achieves intrinsic stability against environmental variations. This eliminates the need for additional sensing and control components, resolving the contradiction between reliability and device complexity.
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 maintains even image density and stable toner charging and transporting properties across environmental variations, reducing particle separation and aggregation, thus enhancing charging stability and device performance.
Implementation Method 1
a binder resin having a solubility parameter (SP) value in the range of 7.5 to 9.0; and roughness-imparting particles made from a resin having an SP value that has a difference from the SP value of said resin of 2 or less in the absolute value thereof
Data Source
AI summary
A developing roller has a surface layer composed of a binder resin having an SP value in the range of 7.5 to 9.0, and roughness-imparting particles made from a resin having an SP value that has a difference from the SP value of the resin of 2 or less in the absolute value thereof. The roughness-imparting particles are dispersed in the binder resin. A developing device is provided with the developing roller. An image-forming apparatus is provided with the developing device equipped with the developing roller.