Dual Transfer Image Forming Layout for Toner Alignment
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Solution Overview
Problem
The fluctuation in transport speed of paper passing through a paper position adjusting roll is simultaneously transmitted to two secondary transfer positions, leading to misalignment of toner images in an image forming apparatus using multiple image forming units.
Innovation Solution
The image forming apparatus is configured such that the distance between the paper position adjusting roll and the secondary transfer positions is set longer than the maximum paper length for the largest paper size, and the distance between the fixing position and the secondary transfer position is set longer than the maximum paper length, while ensuring the distance between the paper position adjusting roll and the secondary transfer position for the smallest paper size is shorter than the minimum paper length, thereby preventing speed fluctuations from being transmitted to multiple transfer positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between the paper position adjusting roll and secondary transfer positions is shortened to improve productivity, then paper transport speed increases, but speed fluctuations are transmitted to multiple secondary transfer positions causing toner image misalignment
Solution Approach 1:
The patent divides the paper transport path into separate zones by positioning the paper position adjusting roll such that it can only contact papers of specific size ranges. This segmentation ensures that speed adjustments are isolated to specific transfer positions rather than being transmitted across all positions, thereby maintaining image alignment while allowing efficient transport.
Solution Approach 2:
The patent applies local quality by creating different distance relationships between the paper position adjusting roll and secondary transfer positions based on paper size. For papers within a certain size range, the distance is configured so that the roll contacts only one transfer position, providing localized speed adjustment without affecting other positions, thus preventing misalignment.
2Manufacturing precision
If the distance between the paper position adjusting roll and secondary transfer positions is increased to prevent speed fluctuation transmission, then toner image alignment is maintained, but the transport path length increases reducing productivity
Solution Approach 1:
The patent employs dynamic positioning where the effective distance between the paper position adjusting roll and secondary transfer positions varies based on paper size. The roll is positioned at a distance that dynamically adapts to different paper lengths, ensuring optimal contact with only one secondary transfer position for each paper size, thereby maintaining alignment without excessive path length.
Solution Approach 2:
The patent changes the geometric parameter of the paper position adjusting roll position relative to secondary transfer positions. By setting the distance to a specific value that corresponds to the maximum paper size, the system ensures that for all practical paper sizes, the roll can only reach one secondary transfer position, preventing speed fluctuation transmission while minimizing path length.
3Manufacturing precision
If multiple image forming units are used to expand color gamut, then image quality is improved, but the complexity of synchronizing multiple secondary transfer positions increases
Solution Approach 1:
The patent extracts the speed control function from the central control system and implements it locally at the paper position adjusting roll. By configuring the roll's position such that it naturally contacts only one secondary transfer position for each paper size, the system eliminates the need for complex electronic synchronization between multiple image forming units, thereby reducing control complexity while maintaining image quality.
Data Source
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AI summary
An image forming apparatus includes: a first image forming unit that includes plural first image forming sections and a first intermediate transfer member on which a toner image formed by the plural first image forming sections is primarily transferred; a second image forming unit that is provided on a downstream side of the first image forming unit in a paper transport direction and includes plural second image forming sections and a second intermediate transfer member on which a toner image formed by the plural second image forming sections is primarily transferred; a first secondary transfer section that is provided corresponding to the first image forming unit and secondarily transfers the toner image formed on the first intermediate transfer member onto paper transported on a paper transport path; a second secondary transfer section that is provided corresponding to the second image forming unit and secondarily transfers the toner image formed on the second intermediate transfer member onto paper transported on a paper transport path; and a paper position adjusting roll that transports fed paper, at a predetermined timing, to a first secondary transfer position at which the first secondary transfer section performs secondary transfer, in which a distance between the paper position adjusting roll and a second secondary transfer position at which the second secondary transfer section performs the secondary transfer is longer than a maximum paper length that is a transport-direction length of paper having a largest paper size among sheets of paper having a probability of being used.