Cleaning Blade Free-Length Layout to Prevent Toner Blade Turning-Up
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Solution Overview
Problem
Existing image forming apparatuses using blade cleaning devices face issues such as blade turning-up, squeaking, and chattering due to high friction between the elastic blade and the image bearing member, which can lead to improper cleaning and noise.
Innovation Solution
The image forming apparatus is designed with a cleaning member that includes an elastic blade with varying free lengths at opposite end portions, where the average free length on the outside of the developing region is at least 1.2 times the average free length within the developing region, and the difference in free lengths is maintained within specific limits to prevent blade turning-up while ensuring effective cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the elastic blade is contacted to the surface of the image bearing member to opposite the surface along the movement direction (counter type cleaning), then the cleaning property is improved, but the frictional force increases causing blade turning-up, squeaking, and chattering
Solution Approach 1:
The patent applies local quality by making the free length of the elastic blade non-uniform along its longitudinal direction. Specifically, the free length at the end portion is made longer than the free length at the central portion, creating different mechanical properties in different regions of the blade. This allows the blade to have reduced friction and prevent turning-up at the end portions while maintaining adequate cleaning contact pressure in the central region, thereby resolving the contradiction between cleaning effectiveness and harmful friction effects.
2Stability of the object's composition
If the free length of the elastic blade at the end portion is made longer to suppress blade turning-up, then the blade stability is improved, but the cleaning effectiveness may be reduced if the region is too broad
Solution Approach 1:
The patent precisely controls the spatial distribution of the free length by defining specific regions: a first region where the free length is longer (suppressing turning-up) and a second region where the free length is shorter (maintaining cleaning effectiveness). The boundary between these regions is carefully positioned to ensure that the longer free length region does not extend too broadly, thus preventing loss of cleaning effectiveness while still achieving blade stability.
Solution Approach 2:
The patent changes the geometric parameter of the elastic blade by making the free length non-uniform along the longitudinal direction. This parameter change is quantified by specifying that the free length at the end portion is longer than at the central portion, with specific regional definitions that control the magnitude and distribution of this parameter change to balance stability and cleaning effectiveness.
3Ease of manufacture
If the free length of the elastic blade is made uniform, then the manufacturing simplicity is maintained, but blade turning-up occurs due to high friction at the end portions
Solution Approach 1:
Instead of using a uniform free length throughout the blade, the patent introduces local quality variation by making the free length non-uniform along the longitudinal direction. The end portions have longer free length while the central portion has shorter free length, which can be implemented through controlled bonding or support structures during manufacturing. This localized modification prevents blade turning-up at the friction-prone end portions while maintaining reasonable manufacturing complexity.
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 design effectively suppresses blade turning-up and improper cleaning, maintaining cleaning efficiency and reducing noise, while ensuring the elastic blade maintains adequate contact pressure to remove residual toner effectively.
Implementation Method 1
a frictional force between the elastic blade and the image bearing member becomes large
Implementation Method 2
an elastic blade of which free end portion contacts the surface of the image bearing member
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developer carrying member, and a cleaning member including an elastic blade and a regulating portion. When an average of a free length L1 [mm] of the elastic blade in the image bearing region in the widthwise direction of the elastic blade is an average free length L1a [mm], an average of a free length L2 [mm] of the elastic blade on an outside of the developing region in the widthwise direction of the elastic blade is an average free length L2a [mm], and an absolute value of a difference between the average free length L1a and the average free length L2a is a free length difference ΔL [mm], the following relationships are satisfied:L2a≥1.2×L1a,L2≥L2a-ΔL×0.2,andL1≤L1a+ΔL×0.2.