Cleaning Blade Surface Roughness for Photosensitive Drum Torque

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Solution Overview

Problem

In image forming apparatuses, reducing the driving torque of the photosensitive drum to lower power consumption while preventing toner slip-off and contamination of the charging member, which can cause image defects like vertical streaks.

Innovation Solution

The image forming apparatus is designed with a cleaning blade that has a specific dynamic hardness and a set angle with the photosensitive drum, along with a surface roughening treatment to reduce the contact surface area, thereby minimizing toner slip-off and maintaining low driving torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cleaning blade is strongly brought into contact with the photosensitive drum to improve cleaning capability, then the removal of residual toner is enhanced, but the driving torque of the photosensitive drum increases significantly

Engineering Contradiction:
Improvecleaning capabilityVSAvoiddriving torque
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The invention changes the surface roughness parameter of the photosensitive drum to a specific range (Ra: 0.05 to 0.2 μm) to optimize the balance between cleaning capability and driving torque. This parameter change allows the cleaning blade to effectively remove residual toner while minimizing the increase in driving torque.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cleaning blade is designed with elasticity to dynamically adjust its contact pressure with the photosensitive drum surface. The elastic portion can deform to adapt to surface irregularities, maintaining effective cleaning contact while reducing the peak forces that would increase driving torque.

Inventive Principle:
Principle #15Dynamics

2Force

If the surface roughness of the photosensitive drum is reduced to lower driving torque, then power consumption decreases, but the cleaning efficiency may be compromised

Engineering Contradiction:
Improvedriving torqueVSAvoidcleaning efficiency
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The invention specifies a precise surface roughness range (Ra: 0.05 to 0.2 μm) that is smoother than conventional surfaces, thereby reducing driving torque and power consumption while maintaining sufficient cleaning efficiency through the optimized roughness characteristics.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The surface roughness is optimized specifically in the contact region with the cleaning blade, allowing localized improvement in torque characteristics without compromising the overall cleaning performance of the photosensitive drum surface.

Inventive Principle:
Principle #3Local quality

3Force

If the contact surface area between the cleaning blade and photosensitive drum is reduced to lower torque, then power consumption is reduced, but toner may slip off the cleaning blade causing image defects

Engineering Contradiction:
Improvedriving torqueVSAvoidtoner slip-off
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

By optimizing the surface roughness to a specific range (Ra: 0.05 to 0.2 μm), the invention creates a surface that provides sufficient mechanical interlocking for toner retention while maintaining low contact area to reduce driving torque.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The photosensitive drum surface is treated to create a composite structure with optimized roughness characteristics that combine low friction properties for torque reduction with sufficient adhesion properties to prevent toner slip-off during the cleaning process.

Inventive Principle:
Principle #40Composite materials

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 image problems caused by toner contamination while achieving a reduced driving torque, thus enhancing the efficiency and longevity of the image forming apparatus.

Implementation Method 1

the cleaning blade is strongly brought into contact with and rubbed against the photosensitive drum

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the surface roughness of the photosensitive drum is controlled... the torque is reduced by reducing the contact surface area between the cleaning blade and the photosensitive drum

Methodology Applied
Scientific EffectSurface roughness:

Data Source

PatentEP4123383B1Image forming apparatus
Publication Date: 2025.06.11 CANON KK
  • EP4123383B1 patent drawingFigure 1
  • EP4123383B1 patent drawingFigure 2
  • EP4123383B1 patent drawingFigure 3

AI summary

An image forming apparatus including: an image bearing member; a developing member to supply a developer to the image bearing member; and a cleaning member to clean a peripheral surface of the image bearing member in contact with the peripheral surface, wherein a plurality of grooves extend in a circumferential direction on the peripheral surface, and have a width in a generatrix direction of the peripheral surface within a range of at least 0.5 µm and not more than 40 µm, and are formed to be side by side in the generatrix direction; the number of the grooves is at least 20 and not more than 1000 per a width of 1000 µm in the generatrix direction of the peripheral surface; and an average depth (Rvk) of a valley of a projection under a core section of a roughness curve of the peripheral surface is 0.08 µm or less.