Photoreceptor Surface Roughness for Raindrop Defect Prevention
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Solution Overview
Problem
The occurrence of raindrop-like image defects during continuous printing of high-toner-consuming images, such as solid images on blue backgrounds, in electrophotographic image forming methods, due to toner particles and additives slipping through the cleaning device and adhering to the photoreceptor surface.
Innovation Solution
An electrophotographic image forming method using a photoreceptor with a specific surface roughness profile, characterized by a ratio of average length of surface roughness profile elements (RSm) to toner median diameter (D50) from 0.4 to 2.0 and skewness (Rsk) from −3.0 to 0.0, combined with a lubricant like zinc stearate applied to the photoreceptor surface to prevent toner particles from adhering to the photoreceptor surface irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photoreceptor surface is made harder to improve anti-wearing property, then durability is improved, but surface property degradation occurs making it difficult to remove foreign materials
Solution Approach 1:
The invention changes the surface roughness parameters (RSm and Rsk) of the photoreceptor to specific ranges (RSm: 0.01-10 μm, Rsk: -5.0 to 0.0) to create a balance between durability and foreign material removability. This parameter optimization allows the surface to maintain hardness while preventing excessive degradation that would trap foreign materials.
Solution Approach 2:
The invention applies local quality by creating specific surface roughness characteristics in different directions (using RSm for vertical roughness and Rsk for asymmetry). This directional control of surface properties allows the photoreceptor to have enhanced durability in one aspect while maintaining ease of cleaning in another, resolving the contradiction between hardness and foreign material removal.
2Productivity
If toner is applied for high consumption printing (solid images), then productivity is improved, but raindrop-like image defects occur due to toner particles adhering to photoreceptor surface
Solution Approach 1:
The invention performs preliminary action by pre-configuring the photoreceptor surface with specific roughness characteristics (RSm: 0.01-10 μm, Rsk: -5.0 to 0.0) before printing operations. This pre-established surface structure prevents toner particles from adhering during high-consumption printing, thereby avoiding raindrop-like defects while maintaining high productivity.
Solution Approach 2:
The invention changes the surface roughness parameters to specific ranges that optimize both high-speed printing capability and image quality. By controlling RSm and Rsk within defined boundaries, the surface can handle large toner volumes during solid image printing without causing the adhesion problems that lead to raindrop-like defects.
3Manufacturing precision
If cleaning device operates to remove toner particles, then image quality is improved, but toner particles slip through and adhere to photoreceptor surface causing defects
Solution Approach 1:
The invention applies beforehand cushioning by pre-establishing a protective surface roughness structure (RSm: 0.01-10 μm, Rsk: -5.0 to 0.0) that acts as a barrier against toner particle adhesion. This pre-configured surface property cushioning effect prevents particles that escape the cleaning device from adhering to the photoreceptor, thereby maintaining image quality without compromising cleaning effectiveness.
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 enables the production of high-resolution images without raindrop-like or streak image defects, even during continuous printing with high toner consumption, by effectively capturing and maintaining the lubricant on the photoreceptor surface, preventing toner particles from adhering and causing defects.
Implementation Method 1
a lubricant like zinc stearate applied to the photoreceptor surface to prevent toner particles from adhering to the photoreceptor surface irregularities
Data Source
AI summary
An electrophotographic image forming method is disclosed. The method includes electrically charging a photoreceptor, imagewise exposing the photoreceptor so that a latent image is formed on the photoreceptor, supplying a lubricant on a surface of the photoreceptor, and developing the latent image with a toner so that a toner image is formed on the photoreceptor, transferring the toner image and cleaning the photoreceptor, in which the photoreceptor has an electro-conductive substrate, a photosensitive layer and a protective layer containing inorganic particles, a ratio RSm/D50 of an average length of surface roughness profile element in the direction making a right angle with the driving direction of the photoreceptor RSm (μm) to a number-based median diameter of the toner D50 is from 0.4 to 2.0, and a skewness of the surface roughness profile of the photoreceptor in the direction making a right angle with the driving direction of the photoreceptor Rsk is from −3.0 to 0.0.