Transfer Belt Roller Diameter Ratio for Color Registration
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Solution Overview
Problem
In tandem color systems, it is challenging to properly superimpose toner images of different colors due to fluctuations in the transfer belt's running speed, leading to color displacement and unevenness, which are caused by factors like variations in roller diameters and belt tension.
Innovation Solution
The image forming apparatus ensures that the outer diameters of the drive and driven rollers, including the thickness of the transfer belt, satisfy a specific ratio (D2 = N·D1), where N is a positive integer, to synchronize the rotational fluctuations of these rollers, thereby aligning the timing of color unevenness across all toner images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the transfer belt is driven by rollers with different outer diameters, then the device can be manufactured with standard components, but the running speed of the transfer belt fluctuates causing color displacement
Solution Approach 1:
The patent applies parameter changes by establishing a specific mathematical relationship between the outer diameters of the drive roller and driven roller. By setting the driven roller's outer diameter to N times the drive roller's outer diameter (where N is a positive integer), the system compensates for speed fluctuations caused by roller diameter differences, thereby maintaining precise color superimposition while allowing manufacturing flexibility
2Manufacturing precision
If the outer diameters of drive and driven rollers are made equal, then color superimposition precision is improved, but the complexity of selecting and manufacturing rollers increases
Solution Approach 1:
Instead of requiring equal diameters, the patent introduces a flexible parameter relationship where the driven roller's diameter is N times the drive roller's diameter. This approach maintains color superimposition precision while simplifying manufacturing, as rollers with standard diameter series can be used as long as they satisfy the N:1 ratio
3Device complexity
If the transfer belt thickness is not accounted for in roller diameter measurements, then the measurement process is simplified, but the running speed fluctuation increases
Solution Approach 1:
The patent addresses this by defining the outer diameter measurement to explicitly include the transfer belt thickness. The drive roller's outer diameter D1 is measured as the diameter of the roller plus the belt thickness, and the driven roller's outer diameter D2 is similarly measured. This ensures accurate speed synchronization while maintaining simple measurement procedures
Data Source
AI summary
An image forming apparatus has a plurality of developing units for developing toner images of different colors, an intermediate transfer belt for transferring the toner images of the respective colors onto a surface of the belt or onto a recording sheet transported over the belt surface, a first or drive roller for driving the belt while the belt is wound around the first roller, a second or driven roller and a tension roller, which is driven along with the driving of the belt driven by the first roller. The image forming apparatus satisfies a relation defined by the following equation:D2=N·D1where D1 is a belt-inclusive outer diameter of the first roller where the belt is wound, including the thickness t of the belt, D2 is an outer diameter of the second roller, and N=n or 1/n where n is a positive integer.