Rotating Tension Bar for Roll-to-Roll Printing Slack
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Solution Overview
Problem
In large format printing apparatuses using a roll-to-roll system, uneven tension distribution due to differences in transport path lengths leads to medium slack, twisting, and wrinkling, as the existing tension application units concentrate tension obliquely, causing unbalanced forces and repeated cycles of slack increase.
Innovation Solution
A printing apparatus with a tension application unit featuring a pair of arms, a rotational fulcrum, and a tension bar supported by a counterweight, where the counterweight's center of gravity is lower and opposite to the tension bar's, allowing the tension bar to rotate from an upper to a lower limit position during multiple transport cycles, reducing the number of windings and minimizing slack accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tension bar is caused to rock in a fixed angular range to maintain tension within a predetermined range, then the tension of the medium is kept stable, but the angular range must be narrowed and the transport and winding operations must be repeated frequently
Solution Approach 1:
The tension application unit transitions from a fixed angular range rocking mechanism to a dynamic mechanism where the tension bar can be rotated between upper and lower limit positions. The arms are made rotatable about a rotational fulcrum, allowing the tension application point to move dynamically along the medium width direction, enabling tension control over a larger transport distance without frequent winding operations
Solution Approach 2:
The invention adds a rotational dimension to the tension application mechanism by introducing arms that can rotate about a rotational fulcrum. This allows the tension bar to move not only in the vertical direction but also in the width direction of the medium, creating a two-dimensional movement space that expands the effective control range and reduces the need for frequent winding
2Force
If the center of gravity position is concentrated on the tension bar to apply tension, then the tension application is direct and effective, but the angular range must be narrowed to maintain tension within the predetermined range
Solution Approach 1:
The invention introduces a counterweight member with its center of gravity positioned opposite to the tension bar's center of gravity relative to the rotational fulcrum. This counterweight balances the moment caused by the tension bar, allowing the arms to rotate through a larger angular range while maintaining tension within the predetermined range. The counterweight effectively compensates for the weight of the tension bar, enabling greater rotational freedom
3Length of moving object
If there is a difference in transport path length from one end side to the other end side of the transport roller to the winding unit, then the medium can be transported, but slack arises on the short side and high tension is generated unevenly on the long side
Solution Approach 1:
The invention applies different tension characteristics to different locations of the medium by allowing the tension bar to be positioned at different locations in the width direction. The tension application point can be adjusted locally to compensate for path length differences, applying higher tension to sections needing it and reducing tension where path length is shorter, thereby achieving more uniform tension distribution across the entire medium width
Solution Approach 2:
The arms and rotational fulcrum act as intermediaries between the tension application unit and the medium. By rotating the arms about the fulcrum, the system can adjust the tension application point and distribute tension more evenly across different transport paths, mediating the effect of path length differences on tension uniformity
4Productivity
If the winding unit is driven repeatedly to wind the medium, then the medium is collected on the winding unit, but slack accumulates and twisting and wrinkling may arise
Solution Approach 1:
The dynamic rotation of the tension application unit allows it to adapt to varying transport conditions and maintain proper tension over longer periods. By adjusting the arm rotation and tension bar position dynamically, the system can compensate for slack accumulation and prevent the conditions that lead to twisting and wrinkling, enabling less frequent winding operations while maintaining medium quality
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 configuration reduces the number of windings, minimizes slack, and prevents twisting or wrinkling, thereby improving the quality of the wound medium by maintaining consistent tension and balancing forces across the transport path.
Implementation Method 1
the tension application unit includes a counterweight; a center of gravity position of the counterweight is provided lower in a vertical direction than a straight line which joins the rotational fulcrum and a center of gravity position of the tension bar
Data Source
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Figure 2
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AI summary
A printing apparatus (1) includes a transport unit (2) which includes a transport roller pair (23) which transports a medium (6) in a transport direction, a printing unit (3) which prints onto the medium (6), a winding unit (22) which winds the printed medium (6), and a tension application unit (5) which applies a tension to the medium (6) between the transport roller pair (23) and the winding unit (22), in which the tension application unit (5) includes a pair of arms (54) which are capable of rotating and a tension bar (55) which is supported on one end of the arms (54) and comes into contact with the medium (6), and in which the tension bar (55) is rotated from an upper limit position to a lower limit position by transportation of the transport unit (2) being performed two or more times.