Print Head Gap Adjustment for Continuous Sheet Splice Avoidance
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Solution Overview
Problem
High-speed printing of continuous sheets with splices can result in image failure and increased ink mist due to the risk of the splice contacting the print head, as existing systems lack specific unprintable area settings, leading to positional displacement of ink dots and inadequate gap management.
Innovation Solution
A printing apparatus with a sensing unit to detect splices, an adjusting mechanism to temporarily increase the gap between the print head and the sheet, and a control unit to set unprintable areas on both sides of the splice, ensuring the splice does not contact the print head, with unprintable areas set to accommodate the length of the print heads and sheet movement during gap adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet conveyance speed is increased for high-speed printing, then printing productivity is improved, but the distance the sheet advances during the print head movement period increases, causing the splice to reach under the print head before the print head is completely raised
Solution Approach 1:
The print head is raised in advance before the splice reaches the printing position. The control unit determines the raised position based on the splice position detected by the optical sensor, and raises the print head to that position before the splice arrives, preventing contact before it occurs.
Solution Approach 2:
The optical sensor continuously detects the splice position on the continuous sheet and feeds this information back to the control unit. The control unit uses this real-time feedback to dynamically adjust the print head raised position and timing, ensuring the print head is at the correct position when the splice passes underneath.
2Productivity
If printing is started before the splice leaves completely from under the print head, then productivity is improved, but the gap between the nozzle surface and the sheet becomes larger than normal, causing positional displacement of ink dots and image failure
Solution Approach 1:
The print head is lowered to the printing position in advance after the splice has passed. The control unit determines the lowered position based on the splice position detected by the optical sensor, and lowers the print head to that position before the next printing operation begins, ensuring the gap is restored to normal before printing resumes.
Solution Approach 2:
The optical sensor continuously monitors the splice position and provides feedback to the control unit. The control unit uses this feedback to dynamically adjust the print head lowered position and timing, ensuring the print head is at the correct printing position when normal printing operations resume after the splice passes.
3Reliability
If the print head is retracted to avoid splice contact, then contact prevention is achieved, but the period required for the print head to move upward and downward increases, reducing printing productivity
Solution Approach 1:
The print head performs localized position adjustments only in the specific region where the splice is detected. Instead of complete retraction and extension cycles, the print head raises to a determined raised position and lowers to a determined lowered position based on the splice location, minimizing unnecessary movement while ensuring splice avoidance and maintaining printing efficiency.
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
Prevents printing on splices and avoids contact between the splice and the print head, maintaining image quality by ensuring the gap is adequately managed, reducing ink mist and positional displacement of ink dots.
Implementation Method 1
an optical sensor, set unrecordable areas including the splices
Data Source
AI summary
An apparatus includes an adjusting mechanism configured to change a gap between a print head and a continuous sheet, and the adjusting mechanism controls the gap to be larger than that at the time of printing when a splice of the continuous sheet passes the print head. An unprintable area is set on each of the upstream side and the downstream side of the splice, each having at least a width corresponding to a sum of a length of the plurality of print heads in the direction of sheet conveyance and a distance of movement of the continuous sheet in a period required for the adjusting mechanism to change the gap, and the printing is continued while avoiding the unprintable area.