Photoreceptor Protective Layer Cracking via Carrier Size Control
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Solution Overview
Problem
In image forming apparatuses using electrophotographic photoreceptors with inorganic protective layers, carrier scattering occurs due to large carrier particles, leading to stress and cracking, especially during start or stopping, which results in image defects like streaks.
Innovation Solution
The use of an electrophotographic photoreceptor with an organic photosensitive layer and an inorganic protective layer, combined with a developer containing toner and a carrier where the ratio of carrier particles with a particle diameter of 50 μm or greater is limited to less than 1%, reducing stress on the photoreceptor and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier particles with large particle diameter (50 μm or greater) are used in the developer, then the developer has good flowability and filling properties, but carrier scattering occurs causing stress and cracking in the inorganic protective layer
Solution Approach 1:
The patent changes the particle size parameter of carrier particles by specifying that particles with diameter of 50 μm or greater should occupy 1% or less by number in the carrier. This parameter modification resolves the contradiction by maintaining good flowability through controlled particle size distribution while preventing carrier scattering that causes cracking in the inorganic protective layer.
2Stability of the object's composition
If carrier particles with large particle diameter are used, then the developer maintains stability, but stress concentration occurs during start or stopping leading to cracking
Solution Approach 1:
The patent modifies the particle size parameter of carrier particles by limiting the number ratio of particles with diameter of 50 μm or greater to 1% or less. This maintains developer stability while reducing stress concentration on the inorganic protective layer during start or stopping operations, thereby preventing cracking.
3Productivity
If conventional carrier particles are used, then the developer performs well, but image defects such as streaks occur due to cracking
Solution Approach 1:
The patent changes the particle size parameter of carrier particles by specifying that particles with diameter of 50 μm or greater should occupy 1% or less by number. This maintains good developing performance while preventing cracking in the inorganic protective layer, thereby eliminating image defects such as streaks and ensuring high image quality.
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 configuration minimizes carrier scattering and prevents cracking in the inorganic protective layer, thereby reducing image defects and ensuring stable image formation.
Implementation Method 1
a charging unit that charges a surface of the electrophotographic photoreceptor; an electrostatic latent image forming unit that forms an electrostatic latent image on a charged surface
Implementation Method 2
carrier scattering occurs due to large carrier particles, leading to stress and cracking, especially during start or stopping, which results in image defects like streaks
Data Source
AI summary
An image forming apparatus includes an electrophotographic photoreceptor that includes a conductive substrate, an organic photosensitive layer provided on the conductive substrate, and an inorganic protective layer provided on the organic photosensitive layer; a charging unit that charges a surface of the electrophotographic photoreceptor; an electrostatic latent image forming unit that forms an electrostatic latent image on a charged surface of the electrophotographic photoreceptor; a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to thereby form a toner image, by using a developer which contains a toner, and a carrier in which a ratio occupied by carrier particles having a particle diameter of 50 μm or greater is equal to or smaller than 1% by number; and a transfer unit that transfers the toner image to a surface of a recording medium.