Grooved Idler Roller for Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses using metal rollers as support and transfer rollers face issues with dust and developer entering the intermediate transfer belt, leading to tension lines and uneven image density due to varying contact pressures and gaps, resulting in streak-like deformations and density irregularities in the transferred images.
Innovation Solution
The implementation of a transfer unit with groove-less metal primary transfer rollers having a maximum surface height of 25 µm or less and a grooved idler roller with a spirally formed groove on its surface to prevent dust accumulation and maintain consistent contact pressure, thereby reducing tension lines and uneven current, ensuring uniform image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal rollers are used as support rollers for stretching the intermediate transfer belt, then the structural strength and stability are improved, but dust or developer enters between the support roller and the belt causing local pressure increase and tension lines
Solution Approach 1:
The support roller surface is designed with local groove structures that create zones of different functionality: the grooves allow dust and developer to enter without creating pressure points, while the ridges between grooves maintain contact pressure for proper belt support. This local differentiation resolves the contradiction between needing structural strength and avoiding tension lines.
2Ease of manufacture
If transfer rollers have portions with large gap to the belt and portions with small or no gap, then the manufacturing tolerance is easier to control, but uneven current arises in the axial direction causing uneven density in transferred images
Solution Approach 1:
The transfer roller surface parameters are modified by adding groove structures that change the electrical field distribution. The grooves create a more uniform current path through the belt by preventing charge accumulation at gap variations, thus maintaining image density uniformity even when manufacturing tolerances result in variable gaps.
3Object-affected harmful factors
If the surface roughness of the transfer roller is reduced to prevent tension lines, then the occurrence of tension lines is decreased, but the contact pressure uniformity may be compromised affecting transfer quality
Solution Approach 1:
The transfer roller surface is segmented into multiple functional zones using groove structures. The grooves themselves have reduced roughness to prevent tension lines, while the ridges between grooves maintain adequate contact pressure. This segmentation allows simultaneous achievement of both low tension lines and uniform contact pressure distribution.
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 prevents the occurrence of tension lines and uneven image density, resulting in improved image quality by maintaining consistent contact pressure and reducing electrical stress, thus ensuring high-quality image transfer without streaks or density irregularities.
Implementation Method 1
The idler roller 61 has a groove 70 formed on the surface... dust or a developer may enter the inside of the intermediate transfer belt. If dust enters between a support roller and the belt, the pressure applied to the belt will be locally increased
Implementation Method 2
toner images are transferred from photosensitive drums as image bearing members to an intermediate transfer belt... when a voltage is applied to the transfer rollers
Data Source
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AI summary
An idler roller as at least one of a plurality of support rollers for stretching an intermediate transfer belt is a metal roller having a groove formed on a metal surface. A primary transfer roller is a metal roller having a metal surface with a smaller maximum surface height than the idler roller.