Cleaning Blade Hardness and Contact Width for Drum Wear
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Solution Overview
Problem
In image forming apparatuses, mechanical abrasion of the photosensitive drum can lead to abrasion particles accumulating between the drum and the cleaning blade, causing toner to pass through the gap and result in image defects due to unstable cleaning blade behavior and wear.
Innovation Solution
The image forming apparatus features a photosensitive drum with a surface subjected to mechanical abrasion and a cleaning blade with a rubber member having a hardened surface layer, where the contact width between the blade and the drum is optimized to prevent toner passing by reducing the contact width and increasing the contact pressure, ensuring effective removal of abrasion particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface of the photosensitive drum is subjected to mechanical abrasion to improve durability, then wear resistance is improved, but abrasion particles remain on the surface and accumulate in the nip between the drum and cleaning blade, causing toner to pass through and image defects
Solution Approach 1:
The cleaning blade is designed with non-uniform hardness: the distal end portion (contacting the drum surface) has higher hardness than the base end portion. This local quality variation allows the blade to effectively remove abrasion particles from the drum surface while maintaining structural integrity and reducing wear on the blade itself.
Solution Approach 2:
The contact force per unit length of the cleaning blade with the drum surface is precisely controlled within 0.196 N/cm to 0.490 N/cm. This parameter optimization ensures sufficient cleaning pressure to remove abrasion particles while preventing excessive force that could cause toner passing through gaps.
2Reliability
If the contact force between the cleaning blade and photosensitive drum is increased to improve cleaning effectiveness, then abrasion particle removal is improved, but the cleaning blade becomes unstable and toner passes through gaps
Solution Approach 1:
The contact force per unit length is precisely controlled within the range of 0.196 N/cm to 0.490 N/cm. This optimized parameter range ensures sufficient cleaning pressure to effectively remove abrasion particles while maintaining blade stability and preventing toner from passing through gaps.
Solution Approach 2:
The cleaning blade has non-uniform hardness distribution with the distal end portion being harder than the base end portion. This local quality variation allows different regions of the blade to serve different functions: the harder distal end provides stable contact and effective cleaning, while the softer base end maintains flexibility and stability.
3Reliability
If the contact width between the cleaning blade and photosensitive drum is reduced to increase contact pressure and remove abrasion particles, then cleaning effectiveness is improved, but the cleaning process becomes less stable
Solution Approach 1:
The contact width is precisely controlled within 4 μm to 13.5 μm depending on the contact force level. This optimized contact width range provides sufficient contact pressure to remove abrasion particles while maintaining enough contact area for stable cleaning process operation.
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 effectively suppresses toner passing and improves the wear life of the photosensitive drum, maintaining a stable cleaning process and preventing image defects, even when the cleaning step after abrasion is shortened.
Implementation Method 1
a contact width between the cleaning blade and the opposed object for measurement in each of the measurement recesses is 4 μm or more and 8 μm or less when the contact force per unit length in the longitudinal direction of the cleaning blade is 0.196 N/cm
Data Source
AI summary
A cleaning blade, which is to be brought into contact with a surface of a photosensitive drum, satisfies the following condition. First, the cleaning blade having a free length of 8 mm is brought into contact with an opposed object for measurement having a plurality of measurement recesses each having a partially spherical shape with a depth of 0.7 μm and a radius of 15 μm on a surface so that a linear pressure is 0.196 N/cm and 0.490 N/cm, and a contact angle with respect to the opposed object for measurement is 25°. In this case, a contact width of the cleaning blade in each of the measurement recesses is 4 μm or more and 8 μm or less when the linear pressure is 0.196 N/cm and is 4 μm or more and 13.5 μm or less when the linear pressure is 0.490 N/cm.