Media Advance System Skew Correction via Roller Speed Control
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Solution Overview
Problem
High productivity printing systems face inefficiencies in cutting media before printing, leading to media skew and alignment issues due to the absence of back tension control and repetitive alignment requirements, especially when cutting pre-roll media.
Innovation Solution
Implementing a media advance system with control logic that adjusts the speed ratio between feed and drive rollers and introduces slippage to correct skew, combined with a method to increase media transportation speed to form a bubble for clean cutting, and adjusting the media path length to reduce skew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If media is cut before printing to increase productivity, then cutting efficiency is improved, but media skew and alignment issues worsen due to absence of back tension control
Solution Approach 1:
The system dynamically changes the speed parameter of the feed roller relative to the drive roller to create controlled slippage. By reducing the feed roller speed temporarily, a slack bubble is created that allows the media to realign itself before cutting, thereby maintaining alignment precision while enabling continuous cutting operations
Solution Approach 2:
The system employs dynamic speed adjustment of the feed roller based on real-time detection of media leading edge position and skew conditions. The feed roller speed is modulated during the cutting cycle to create and manage the slack bubble, enabling the system to adapt to varying media conditions and maintain precision throughout continuous operation
2Manufacturing precision
If feed roller speed is reduced relative to drive roller speed to correct skew, then media alignment is improved, but cutting speed and productivity deteriorate
Solution Approach 1:
The system applies periodic speed reduction to the feed roller in sync with the cutting cycle. The speed is reduced only during the specific time window when the media leading edge approaches the cut line, creating slack for alignment correction. After alignment is achieved, the feed roller speed returns to normal, maintaining high productivity during the actual cutting operation
Solution Approach 2:
The system performs preliminary speed reduction and slack creation before the actual cutting moment. By anticipating the need for alignment and creating the slack bubble in advance, the system ensures media is properly aligned before the cut occurs, then immediately resumes normal speed to maintain productivity during the cutting operation
3Productivity
If a bubble is created to allow media stop for cutting, then cutting capability is improved, but back tension control is lost leading to increased skew
Solution Approach 1:
The system uses sensors to continuously monitor the position and orientation of the media leading edge. This feedback information is used by the control system to dynamically adjust the feed roller speed, creating slack only when and where needed to maintain alignment, thereby compensating for the loss of back tension control during bubble formation
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 approach effectively reduces media skew and curling, allowing for higher throughput and precise cutting by introducing controlled slippage and adjusting the media path, thereby improving alignment and cutting efficiency.
Implementation Method 1
reducing a media transportation speed at a feed roller relative to a media transportation speed at a drive roller
Data Source
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AI summary
A method for reducing skew in a media advance system comprises advancing a media from a media roll (6a) through a feed roller (3) towards the nip of a drive roller (4); reducing a media transportation speed at the feed roller (3) relative to the media transportation speed at the drive roller (4) for a predetermined period of time when a leading edge of the media reaches the nip of the drive roller; and cutting the media to a predetermined page size at a position upstream of the feed roller.