Image Forming Apparatus with Convex Toner Surfaces for Heat Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image defects such as image fogging and increased temperature at the end portion of the developing roller in contact developing type image forming apparatuses, along with reduced transfer efficiency and adhesion of toner to other members, are prevalent due to insufficient toner charging and frictional issues.
Innovation Solution
The image forming apparatus and process cartridge employ toner particles with convex portions on their surfaces, characterized by specific dimensions and distributions, and a developer carrier with controlled contact regions to manage friction and charging, along with transfer accelerating particles to enhance transfer efficiency and reduce adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact developing method is used with developer carrier and photosensitive drum in contact, then development efficiency is improved, but temperature increases at end portion of developer carrier causing breakage or toner fusion
Solution Approach 1:
The invention divides the developer carrier surface into multiple regions with different friction coefficients. By creating regions with high friction coefficients and regions with low friction coefficients on the developer carrier surface, the patent segments the contact area to control heat generation locally while maintaining overall development efficiency.
Solution Approach 2:
The invention applies different surface properties to different locations on the developer carrier. Specifically, it creates regions with different friction coefficients at specific positions on the developer carrier surface, allowing local optimization of heat control without compromising the overall development function.
2Reliability
If toner is sealed at end portion of developer carrier, then toner containment is improved, but friction increases in toner non-coated region causing heat generation
Solution Approach 1:
The invention creates regions with different friction coefficients at the end portion of the developer carrier. By forming a region with low friction coefficient in the toner non-coated area, it reduces frictional heat generation while maintaining toner containment through the sealing structure.
3Productivity
If insufficient charge is imparted to toner in regulating unit or mixing unit, then charging speed is improved, but image fogging occurs due to poorly charged or reverse-polarity toner
Solution Approach 1:
The invention introduces a charging member that contacts the photosensitive drum in the developing portion to impart charges to toner particles. This intermediary charging mechanism ensures proper toner charging even when charging in the regulating unit or mixing unit is insufficient, preventing image fogging while maintaining fast charging speed.
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 suppresses image defects, reduces temperature increases, and improves transfer efficiency while minimizing toner adhesion to other components, enhancing the service life and performance of the image forming apparatus.
Implementation Method 1
the apexes of the convex portions on the toner base particle surface enter recessed portions formed between the convex portions on the surface of the image bearing member, thereby a rolling force is generated on the toner
Implementation Method 2
a rolling force is generated on the toner when the image bearing member and the toner base particle come into contact with each other in the developing portion
Implementation Method 3
it has become general use to visualize an electrostatic latent image formed on an image bearing member, such as a photosensitive drum represented by an electrophotographic photosensitive member, with a developer (toner)
Data Source
AI summary
Used is an image forming apparatus including an image carrier and a developer carrier, in which a toner particle of the developer includes convex portions on a surface of a toner base particle, in a horizontal image converted from a cross-sectional image of the toner particle with STEM, when a convex maximum length D and a convex height H are equal to each other, and convex portions having a convex height H of 20 nm or more are defined as convex portions Y, a number-based average of convex widths W in the convex portions Y is at least 40 nm and not more than 200 nm, when a width of the horizontal image is defined as a circumferential length L, and a total of the convex widths W of the convex portions Y is indicated by ΣW, ΣW/L is 0.5 or more.