Rotatable Transfer Nip for Image Sub-magnification Control
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Solution Overview
Problem
Image forming apparatuses face issues with image sub-magnification variations due to differences in toner coverage and sheet thickness, leading to toner coverage and sheet thickness errors that affect image quality.
Innovation Solution
A transfer device with a rotatable image bearer and a secondary transfer roller that satisfies the conditional expression (t1+R)/(t2+R)>0.98, where t1 is the thinnest recording medium thickness, t2 is the thickest recording medium thickness, and R is the radius of curvature of the transfer nip, ensuring consistent linear velocity and reduced errors in image sub-magnification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional transfer device is used, then the transfer process can be completed, but image sub-magnification varies due to differences in sheet thickness and toner coverage
Solution Approach 1:
The transfer roller is made rotatable with the image bearer, creating a dynamic transfer system where both rollers rotate together. This dynamic configuration allows the transfer nip to adapt to different sheet thicknesses while maintaining consistent linear velocity, thereby reducing image sub-magnification variation across different media types
Solution Approach 2:
The patent changes the operational parameters of the transfer device by making the second rotator rotatable with the image bearer and satisfying the conditional expression (t1+R)/(t2+R)>0.98. This parameter adjustment ensures that the linear velocity remains consistent across different sheet thicknesses, improving image sub-magnification consistency while maintaining adaptability to various recording media
2Adaptability or versatility
If the linear velocity varies with sheet thickness, then different thicknesses can be handled, but toner coverage errors and image quality deteriorate
Solution Approach 1:
By making the transfer roller rotatable with the image bearer, the system dynamically adjusts to different sheet thicknesses while maintaining constant linear velocity. This dynamic coupling prevents toner coverage errors that would otherwise occur when linear velocity varies with sheet thickness
Solution Approach 2:
The patent modifies the operational parameters by satisfying the conditional expression (t1+R)/(t2+R)>0.98, which ensures that linear velocity remains consistent across different sheet thicknesses. This parameter control maintains toner coverage accuracy while preserving the ability to handle various recording media thicknesses
3Device complexity
If a fixed transfer nip configuration is used, then the device structure is simple, but image length variation occurs due to sheet thickness differences
Solution Approach 1:
The transfer device uses a dynamic configuration where the second rotator rotates with the image bearer, allowing the transfer nip to naturally adapt to different sheet thicknesses. This dynamic approach maintains image length consistency without requiring complex adjustment mechanisms, thus keeping the device structure relatively simple
Data Source
AI summary
A transfer device includes a rotatable image bearer configured to bear a toner image to be transferred to a recording medium, a first rotator, and a second rotator. The second rotator is configured to contact the first rotator via the rotatable image bearer to form a transfer nip in which the recording medium is sandwiched. The second rotator is rotatable with the image bearer. The transfer device satisfies a conditional expression (t1+R)/(t2+R)>0.98, where t1 represents a thickness of a thinnest recording medium, t2 represents a thickness of a thickest recording medium, and R represents a radius of curvature of the transfer nip.