Media Conveyance Device Slack Control for Reversing Precision
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Solution Overview
Problem
Conventional media conveyance devices face issues with unstable reversing operations, leading to increased stopping time and distance, paper jams, and reduced precision due to inertia and tension-related shifts during the reversing of sheet media in roll form.
Innovation Solution
A conveyance device with an upstream roller, downstream roller, and roll rotating unit, controlled by a unit that creates and manages slack to prevent shifts and ensure precise reversing, including the use of a follower roller and encoder for timely stopping of the roll rotating unit to minimize slack and prevent jams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If tension is applied between the upstream roller and the media roll during reversing operation, then the media can be conveyed in reverse, but the media position shifts and propagates downstream causing jams and reduced precision
Solution Approach 1:
The patent extracts the harmful tension force from the reversing operation by disengaging the upstream roller from the media during reverse conveyance. Only the roll rotating unit applies force to the media, eliminating the tension that causes position shifts and downstream propagation of errors.
Solution Approach 2:
The patent introduces a follower roller as an intermediary element between the upstream roller and the media. This follower roller contacts the media during reversing operation, allowing controlled movement while preventing excessive tension and position shifts.
2Ease of operation
If a predetermined deceleration curve is used to stop the media roll, then the stopping process is controlled, but unstable behavior occurs due to inertia changing with roll diameter increasing stopping time and distance
Solution Approach 1:
The patent implements dynamic control of the reversing operation by adjusting the rotational speed of the roll rotating unit based on real-time conditions. The system transitions from static deceleration curves to dynamic speed adjustment that accounts for changing inertia as the roll diameter decreases during unwinding.
Solution Approach 2:
The patent employs feedback control by monitoring the actual position and speed of the media during reversing operation. The control unit adjusts the roll rotating unit's speed based on this feedback, enabling precise stopping despite varying inertia conditions.
3Use of energy by stationary object
If the upstream roller continues to drive the media during reversing, then continuous conveyance is maintained, but media shifts occur and propagate to downstream components causing jams
Solution Approach 1:
The patent removes the upstream roller's driving function during reversing operation, extracting it from the media conveyance path. This eliminates the source of tension-induced shifts that would otherwise propagate downstream and cause jams.
Solution Approach 2:
The patent implements periodic engagement and disengagement of the upstream roller with the media. The roller is engaged during forward conveyance and disengaged during reversing operation, creating a periodic action pattern that prevents jams while maintaining overall conveyance continuity.
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
The solution enables fast, precise media reversing, prevents paper jams, and improves throughput by controlling slack and inertia, maintaining media position accuracy and reducing the need for larger conveyance path structures.
Implementation Method 1
an upstream roller that rotates forward to convey a medium of a sheet form stored in a roll in a conveyance direction to a conveyance path and to rotate in reverse to move the medium in a reverse direction
Implementation Method 2
a downstream roller that rotates to convey the medium to a processing position
Implementation Method 3
a roll rotating unit that rotates forward to convey the medium in the conveyance direction and to rotate in reverse to rewind the medium
Data Source
AI summary
A conveyance device has a roll rotating unit that rotates a roll of sheet medium forward and in reverse, and a conveyance path along which is an upstream roller and a downstream roller for conveying the medium and cooperate in a reverse and rewind operation. A control unit controls driving of the upstream roller, the downstream roller, and the roll rotating unit, such that, during the reverse and rewind operation, the control unit (i) drives the upstream roller and the roll rotating unit, (ii) stops driving the upstream roller while continuing to drive the roll rotating unit, first slack being created as a result of (i) or (ii), (iii) causes the medium to be nipped at the downstream roller, and (iv) drives the upstream roller while the medium is nipped at the downstream roller to create second slack.