Cleaning Blade Curved Edge Radius for Liquid Ring Prevention
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Solution Overview
Problem
Existing cleaning blades for image forming apparatuses with liquid developers face issues of inadequate contact pressure at the lengthwise ends, leading to liquid developer escape and the formation of 'liquid rings', which contaminate other apparatuses and reduce image quality.
Innovation Solution
A cleaning blade with a curved and linear edge configuration, where the curved portion has an arcuate shape connected tangentially to the linear portion, and a maximum angle between them is not less than 5 degrees, along with a radius of curvature between 240 mm and 320 mm, is designed to ensure effective removal of liquid developer without allowing it to escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the lengthwise end portions of the cleaning edge are provided with curvature to prevent liquid rings, then liquid developer escape is reduced, but contact pressure at the end portions becomes insufficient
Solution Approach 1:
The cleaning blade employs different geometries at different locations: the central portion has a straight cleaning edge for primary liquid developer removal, while the lengthwise end portions have curved edges with larger radius of curvature to prevent liquid ring formation. This local differentiation allows each portion to optimize its function without compromising the other.
Solution Approach 2:
The lengthwise end portions of the cleaning edge are designed with curved surfaces having a larger radius of curvature compared to the central straight portion. This curvature prevents the formation of liquid rings at the ends by altering the flow dynamics of the liquid developer, while the gradual transition maintains adequate contact pressure.
2Shape
If the radius of curvature at the lengthwise end portions is small, then the blade width increases, but contact pressure decreases below the necessary value
Solution Approach 1:
The invention specifies a particular range for the radius of curvature (larger than conventional designs) at the lengthwise end portions. This parameter optimization ensures that the curved portions are wide enough to prevent liquid ring formation while maintaining sufficient contact pressure through the elastic deformation of the blade material.
3Ease of manufacture
If the connection point between straight and curved portions is not smooth, then manufacturing is easier, but contact pressure at the connection point becomes insufficient
Solution Approach 1:
The transition between the straight central portion and the curved end portions is designed with a smooth, continuous curvature. This eliminates abrupt angular connections that would create stress concentrations and pressure drops, ensuring uniform contact pressure along the entire cleaning edge while remaining manufacturable through standard forming processes.
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
The blade effectively prevents liquid developer from escaping and forming 'liquid rings', maintaining image quality by ensuring sufficient contact pressure across the blade's surface, thereby reducing contamination and improving cleaning efficiency.
Implementation Method 1
it moves in the lengthwise direction (toward the lengthwise ends) of the blade, following the minute gaps between the peripheral surface of the image bearing member and the blade (capillary phenomenon), while spreading in the lengthwise direction of the blade
Data Source
AI summary
A cleaning blade for a photosensitive member carrying a liquid developer includes a free end surface provided at one end portion in a height direction of the blade, the free end surface being provided with an edge portion at one end portion of the free end surface with respect to the thickness direction. The edge portion has curved portions and a linear portion therebetween. As seen in the thickness direction, the curved portion includes an arcuate shape portion and is connected with the linear portion such that the linear portion is tangential of the arcuate shape; a height of the blade increases toward the end portion of the blade; a maximum angle formed between the curved portion and the linear portion is not less than 5 degrees; and the curved portion includes a portion having radius of curvature not less than 240 mm and not more than 320 mm.